★ 5

This place is awesome. So much care, effort, and knowledge goes into each week’s cycle of workouts. I started working out with Matt years ago. I’m so glad he finally has his own space. It’s been at least 6 years since I’ve had the energy to get back into it but man I’m so glad I took that step. The format is simple and engaging which for someone with a limited attention span who gets bored with repetition has been great. Every day there’s a new set of exercises. Matt and his staff take care to make sure that each movement is explained, modeled, and monitored. I’ve been working out for about 10 weeks now 4x a week and I am stronger and thinner. As someone who plays sports I am noticeably jumping higher too. Best part- my back doesn’t hurt any more. I recommend this place to anyone who wants to take their fitness journey to the next level. Cannot recommend it enough.

Source: Google

★ 5

I trained with Matt for several years before moving to the East Coast seven years ago. While recently visiting California, I had the opportunity to participate in the Friday conditioning class, and it did not disappoint.
​Matt is still incredibly engaged with the class, expertly motivating the group while providing the individual attention each participant needs. The best part is that the strong family atmosphere I have always appreciated and enjoyed is still present—a direct result of the positive culture Matt has prioritized building over the years.
​So, if you're looking for a top-notch strength and conditioning program that produces results and fosters a community where members truly encourage and motivate each other, I highly encourage you to check it out!

Source: Google

★ 5

This place is amazing! I booked a session using Class Pass. I was totally hooked. Matt is an excellent trainer and made me feel comfortable. I was looking to do resistance training and as a woman in her late 50’s I was a bit nervous. I was contemplating hiring a personal trainer but it was cost prohibitive. Cozmosize Fitness offed semi private training that was exactly the right fit for my fitness goals and my budget. The workouts are challenging but you get through them with everyone cheering you. I love the positive energy and I would encourage anyone to give this place a try

Source: Google

★ 5

I just started going to Cozmosize a few weeks ago but am already hooked! I have little to no experience with resistance training. My only gym experience has been at big fitness centers where you “figure out” the machines and equipment that are available there.

Some things that stand out to me at Cozmosize:
1) The coaching - I appreciate the time the trainers take to properly explain, demonstrate, motivate, and correct.
2) The friendly community - even though I’m newer to the gym, it feels like family. Everyone’s encouraging one another and helping each other out.
3) The workouts - they are challenging but they’re very approachable and customizable for a newbie like myself.

I’m motivated and excited to see my progress here at Cozmosize!

Source: Google

★ 5

Cozmosize are the best Strength and conditioning classes in SCV! Love the atmosphere and everyone is so supportive and friendly especially Matt and Kalena, they are very knowledgeable in this field! I’ve been with Cozmosize for years and my strength and mobility has improved so much and everyday I’m improving! If you are looking for a safe and friendly place to lift weights and condition your heart! These classes are for you!! Don’t wait your body will thank you!

Source: Google

★ 5

Matt is very positive and helpful. He is passionate about the workout programs he creates and skillfully watches form and posture for proper technique. He has the best gym in town!

Source: Google

★ 5

If you’re not seeing results at your current gym or working out on your own, you have to try Cozmo Size Fitness! I’ve been going here for over a year now, and the difference it’s made is incredible. Matt, the owner and trainer, keeps you on a structured full-body program that helps you build muscle fast and safely. The vibe is always positive, and the community is super welcoming, no matter your experience level. It’s a safe, encouraging space where everyone feels supported. Highly recommend!

Source: Google

★ 5

My two daughters and I have been training with Matthew, and we couldn’t be happier. He makes fitness fun, especially for the girls. They’re always excited to go workout!

He is very organized and his plans are clear to follow. His positive energy is amazing and sets the tone for the entire group! It’s such a motivating environment to be a part of. Everyone is very supportive and encouraging. It is a very friendly space. I know I’m in the right place and I’m very excited to see more and more progress week after week.

Source: Google

★ 5

One of the best gyms in Santa Clarita.

Source: Google

★ 5

Best gym ever! I've been working out with Matt for over ten years and it continues to be challenging. Matt does a great job of customizing the workout for you without compromising its effectiveness. If you're looking for a place to start, check out Cozmosize!

Source: Google

★ 5

Matt has been a close friend and gym partner to me for over 15 years now and working out with his program has been transformative! His workout program isn't some Crossfit routine picked from the internet, or the flavor of the month bro-science workout, but a tried and true program that he has adapted over many years. He emphasizes function, form, and mobility over everything, and really strives to cover all the bases so you can grow stronger and fitter in a healthy way.

I have seen him and his brand grow over the last decade and a half and I have seen the lives he has changed with both his enthusiasm for his craft and his genuine drive to make you the best version of yourself physically.

Source: Google

★ 5

If you’re looking for a challenge this is it. Matt and his team not only encourage you to push your limits but educates you on proper technique in the gym. They work with you no matter where you are in your fitness journey. Also an incredible inclusive atmosphere.

Source: Google

★ 5

Matt’s knowledge and understanding of strength & conditioning is second to none. There is a HUGE benefit to having someone with such in depth knowledge preparing workouts for you, add in the fact that you get to workout with great people (at your own pace) and great trainers who are there in case you have questions.

This place is great for any person with any workout level. I’m in the best shape of my life thanks to Matt.

Source: Google

★ 5

Source: Google

★ 5

THE BEST GYM.

Source: Google

★ 5

I have been training at Cozmosize for over 2 years and I can say this is a place like no other.
Matt, the owner of Cozmosize, is not only very professional and knowledgeable but also understands that this is a journey for people, the fitness journey can be fun an hard at the same time, so he created not only an amazing fitness plan but also a community. I enjoy my workouts not only because they are well planned but also because I got to meet lots of amazing people that I now call my fitness friends.
Another thing I have to say about Cozmosize that is totally different from other places is that I feel very supported and supervised by Matt and Kalena while I work out so I feel confident pushing myself to go farther than I would normally push knowing that I'm doing things right.
I look forward to my workouts every day and to see my friends.
Thank you Matt and Kalena for all you do!

Source: Google

★ 5

Cozmosize Fitness has truly flourished since moving to their new location on Railroad Avenue. The spacious facility has transformed into the perfect environment to get stronger, better, and leaner while working toward your fitness goals.

I was first introduced to Matthew Cather by my 17-year-old son 11 years ago, and at the time, I thought it was the toughest workout I had ever attempted. I started training with Matthew twice a week, and now I train five times a week--growing not just physically stronger but also mentally resilient.

As a 52-year-old, I firmly believe that the key to longevity is a combination of weight training, strength, mobility, and conditioning--all of which are seamlessly incorporated into our program at Cozmosize. The dedication, expertise, and sense of community here make every session both challenging and rewarding.

I feel truly blessed to be part of the Cozmo family, and I highly recommend this gym to anyone looking to elevate their fitness journey!

Source: Google

★ 5

CostmoSize is one of the best fitness centers I have ever attended. It is a delightful atmosphere, just like The trainers, Matt and Kalena. I have known Matt for over 10 years, and he has always stood by me. He is fun, genuine, and caring, but most importantly, he is a professional and successful individual, and I am very proud of him. Anyone that hasn't trained with Matt or Kalena, who is a lot of fun, is really missing out!!

Source: Google

★ 5

I honestly wish I had more free time so that I can be able to make it to the gym more often.. BUT I can easily say that I absolutely love everything about this environment. What I appreciate most about this fitness center, is all of the positive motivation that it brings. They work with you one on one, so that everything fits your needs, allowing you to work out comfortably and efficiently. They make sure to push you to your limit, and they never stop believing in each and everyone of us, and that's what I love the most about CozmoSize Fitness. 👍🫶

Source: Google

★ 5

Great training in a fun environment. Everyone pushed to their own limits. Trainers are positive and not overly baring

Source: Google

★ 5

Matthew is such a great trainer. My daughter has gained so much strength since working with him. He is so attentive and cares about form. He corrects her every time she is off. He focuses on her when he’s training her. We love his team and his facility. Matthew truly cares about his clients!!!

Source: Google

★ 5

This is the best gym I have ever been to! The vibe is all inclusive as there are people seemingly in their 20s-60s (me) working out. It’s a no nonsense, yet friendly environment. The variety of activities during the weight training day as well as the aerobic day is quite interesting, creative, and actually fun. The classes are a full 60 minutes, which is a rarity these days when most places cut corners to 45 minutes. One can also go on a run/walk as a group should they want to after the class, but I high tailed it to the donut shop next-door, instead. I felt so much better leaving the gym then when I came in as it truly lifted my mood. The space is huge, immaculate, and easily accessible with good parking. Matt, the owner is hands-on and the staff is well educated regarding body mechanics. I personally work in healthcare and am very skeptical of everything, however, this gym totally has my vote. If you’re looking for a place to both get fit and fit in, look no further than CozmoSize!

Source: Google

★ 5

I started my fitness journey at Cosmosize as a new year's resolution in January of 2024 and I'm proud to say that I've stuck to it mostly because of Matt's guidance and support. Matt's knowledge and experience with strength training allows him to tailor sessions for my individual goals, all the while ensuring that I use proper form and technique to maximize results and prevent injuries. Matt and the rest of the Cosmosize crew are motivating and encouraging. My husband and young adult children also workout here, so it's a family affair and we all LOVE it! I'm SO thankful to be getting stronger by the day and part of the Cosmosize community!

Source: Google

★ 5

Whenever I’m in Newhall, CA, I always make it a point to visit Cozmosize for a fantastic workout. After a great session, I always feel energized and accomplished. Matthew is an excellent trainer and motivator. He always puts me and my Marine buddies through a challenging and rewarding workout. The gym is well-equipped, clean, and the staff is incredibly friendly and knowledgeable. Highly recommended!

Source: Google

★ 5

I am SO happy that I signed up with CozmoSize Fitness!!! I worked with Matt, the owner, years back and was in the best shape of my adult life. Recently, I wanted to/needed to feel stronger, offsetting what work and aging does to the body, and was not excited about progress at a local gym. I completed the one month CosmoSize trial, which was definitely challenging, and decided that a challenge was exactly what I needed. I am now in month three, have dropped inches and weight (folks are noticing!), and enjoy showing up and working out. Most importantly, I value Matt’s knowledge of what I personally need to achieve my goals. You rock Matt!!! Thank you and congratulations!!!

Source: Google

★ 5

Source: Google

★ 5

CozmoSize is a must visit! Everyone there is so nice and friendly, there is a strong sense of community! Matt can clearly communicate how to do an exercise and how to correct your form. Whatever your fitness goals are Matt can help you get there!!

Source: Google

★ 5

Best gym I’ve ever been to. Matt is the best in the business

Source: Google

★ 5

Easily one of the best strength & conditioning gyms in the SCV. Matt is a highly experienced coach which is hard to find nowadays. The group training is completely programmed so it’s not random workouts. The coaches will push you to be better and know how to work with you individually if you have any injuries or restrictions. Amazing community and new facility!

Source: Google

★ 5

I found CozmoSize at a time where I was just learning how to lift and struggling in the gym. The community and great coaching has helped me build strength in more places than just the gym. I have been training at CozmoSize for the past 7 years and can’t be more grateful for all that it’s taught me. CozmoSize does a great job at catering to whatever needs you have while also pushing you to become better every workout!

Source: Google

★ 5

Matthew is an amazing trainer. I say this as I take my 13 year old son and have upmost trust with him. He is courteous, professional and definitely knows how to train !!!!

Source: Google

★ 5

I started going to CozmoSize after suffering two knee injuries my freshman and junior year of high school. Because of Matt, I was able to finish my soccer career on a high note. Now, I can safely say I’m at the strongest I’ve ever been in my life and it’s because Cozmo! CozmoSize has an awesome atmosphere and everyone makes you feel at home. It’s such a tight-knit community and I’m glad to be a part of it. Shoutout to Matt, Kalena and everyone I see at the gym…you guys are the best :)

Source: Google

★ 5

CozmoSize changed the way I live my daily life. Matt and his team are the most caring, energetic and enthusiastic I've had the chance to work out with. I started in horrible shape with various injuries and they helped me to overcome them, get back to "normal". CozmoSize is here for real world strength training that can be applied to daily life for you and your health, not for looks. The humility and judgement free zone make CozmoSize the place for me for years to come!

Source: Google

★ 5

I love working out at CozmoSize Fitness under the watchful of Matt. He’s the best trainer in the SCV! He’s always positive, upbeat, and energetic. He takes real interest in all the members. He’s great at encouraging you to push yourself without being overbearing. I’d definitely recommend it to anyone looking to maximize strength and conditioning. The workouts are varied and challenging, and there is a real sense of community. It’s great!

Source: Google

★ 5

The program itself is absolutely top notch! Matt is the best personal trainer I know. He is so knowledgeable of his craft. He goes above and beyond for his clients. He's passionate about his program. He makes everyone feel welcome. This program is for all levels of fitness. He's cultivated such a welcoming and supportive culture that it doesn't take long for everyone to become friends. He genuinely cares about his clients lives outside the gym and is honestly an wonderful human being.

Source: Google

★ 5

I have been working out with Matt for 13+ years. He has not only been a mentor, but has become a friend. No matter your age or ability level, Matt will meet you where you’re at, and train you in a way that will significantly increase your strength, stamina, and mobility. Through the years, I’ve had major surgeries, fractured bones, and endured severe strains, all unrelated to working out. But, Matt has been there with the modifications and encouragement that I needed to work my way back to a position of strength. Without a doubt, Matt will coach you to be the best that you can be!!!

Source: Google

★ 5

Cozomosize is the best workout I have ever done. As I age this program helps to retain muscle and keep me strong! Matt is inspiring, thorough and incredibly supportive! ❤️

Source: Google

★ 5

Yes, Matt is definitely working miracles up in here! I love the workouts and my progress over the past 6 months has been amazing. I highly recommend his services and this program to anyone looking to improve their physical, mental and emotional health. Thanks, Matt! 😃

Source: Google

★ 5

I’ve been a member for a little over 5 years now and the classes are amazing! I show up do work and the results come. The members are so cool and easy going. Coach Matt and Kalena are phenomenal at what they do. I know I am in good hands.

Source: Google

★ 5

First and foremost, if I can give Matt a million stars, I would!  Matt has a HUGE heart and is extremely knowledgeable in sports training and nutrition.  To say  Matt,  is a great coach is an understatement.  Matt’s unwavering commitment to his clients and  the results he gets them is nothing like I have seen or experienced before.  He is  accommodating and encouraging.  Matt was the reason my son was able to  accomplish his fitness goals.  I’m not surprised with all these 5 star reviews.  I highly encourage anyone,  at any fitness level to stop by and see Matt training his clients, and you will understand why  everyone LOVES Matt.  I PROMISE MATT IS WORTH ALL THE HYPE AND MORE!!!

Source: Google

★ 5

If you want to become the very best;
you need to train with Matt and all his fantastic staff
You will receive the best training without the judgment, rolling eyes you get in gyms
These are serious people about their training

Please come and join the best gym EVER
You will not be disappointed

Love this place and the people

Source: Google

★ 5

CozmoSize Fitness is amazing! I'm so happy that I came across Matt's gym when I was going through my weight lossurgery. He supportive, structured and pushes you to dig deeper with all of your work outs.
💚 love Cozmo. Cozmo for life💚.

Source: Google

★ 5

Best coach in Santa Clarita Valley!

Source: Google

★ 5

My son started with Matt his Freshman year of high school. Matt educated my son about lifting and nutrition. Matt’s attention to form and constant positive encouragement made him have a strong, healthy and knowledgeable work ethic all together.

Source: Google

★ 5

Hands down the best personal training in the valley! There’s plenty of high end equipment that will help you reach all of your physical goals!

Source: Google

★ 5

Matt was instrumental and indispensable in helping my son achieve his strength and agility goals as he went from a good athlete to the absolute beast he has become. Matt’s workouts always had the boys excited and looking forward to training. They worked hard and showed results beyond what we could have imagined. Matt is a caring and involved trainer. He even goes to the high school games to watch the results of his work! His enthusiasm is contagious and motivating.

Source: Google

★ 5

Matt is the best! His dedication to his clients and the results he gets for them are incredible! My daughter's two CIF high school championships wouldn't have happened without Matt and CosmoSize.

Source: Google

★ 5

I've been a member for quite a while, and I've noticed a dramatic change in my athletic strength and ability. Matt is a great coach, very knowledgeable and friendly. He will tailor any workout according to your ability.

Source: Google

★ 5

I have been with Cosmosize since it’s inception over 5 years ago. Matt is the best trainer I ever worked with. Cosmosize is a very well thought out and results-achieving strength and conditioning program. I highly recommend it.

Source: Google

★ 5

I’ve had the time of my life working out at CozmoSize on my vacation in California.

Thanks to Matthew and the team!

Source: Google

★ 5

I started up at Cosmo Size about 4 months ago and I’m not looking back. Matt is an awesome person and definitely knows what he’s talking about in terms of working your muscle groups together. I’ve lost weight and improved my muscle definition and I don’t feel like I’m doing the same monotonous workouts over and over. Working out is fun again!

Source: Google

★ 5

Flexible, accommodating, encouraging and knowledgeable. All qualities that lead to consistent results for me even as my fitness goals change.

Source: Google