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Meet Our Coaches

We want to take a moment to write about the Proven Fitness coaching staff. We believe that coaching is critical to your experience and is something that differentiates Proven. Anyone can become a Crossfit coach by meeting all the requirements of a Level 1 Certification seminar. That certificate is only the foundation for our coaches at Proven. We strive to hold our coaches to a higher standard. Each member of the staff is chosen for their ability to engage with athletes of all levels, their ability to teach athletes to perform movements safely, their enthusiasm for building the Proven community, and their passion for learning and building their own technical expertise.

Each of our Coaches have come up through the ranks as members of CrossFit Proven. Most of our coaches have been learning exclusively from at Proven for 1 to 3 years. They’ve become proficient in our exclusive techniques that have brought success to all of our athletes. This experience is invaluable and is the key ingredient in the application of our coaching techniques. Our coaches engage in continuing education through regular clinics at CrossFit Proven. These clinics focus on the development of their technical expertise. Each coach goes through an inclusive and intensive apprenticeship under the direct tutelage of Matt and each have demonstrated a complete proficiency and efficacy as a coach before they are able to lead classes at CrossFit Proven. Our coaching staff also participates in seminars and receives certifications outside of Proven’s in-house program like; CrossFit’s Olympic Lifting Certification and CrossFit Mobility.

Our staff has a commitment to excellence and constant learning. Proven coaches will always put the needs of Proven athletes first when we are at the box. We know that one thing you ask of us and the other coaches is to give you the best effort we have everyday and ensure you have the best experience possible. We pledge to you, our members and our staff, that we will strive everyday to deliver that best possible experience. Exceptionalism is our standard. Below, you can read brief bios on each of the Proven coaches.

Thank you for making Proven the best place to be a coach.

Matthew Chambers

CrossFit Level 1 Trainer | CMT

Co-Owner, Matthew Chambers has over 20 years experience working as a professional Strength and Conditioning Coach. Professional athletes, homemakers, seniors and children alike have seen great success working with Matt; and you will too! Coach Matt has developed hundreds of coaches all over the world working as an instructor at the National Personal Training Institute since 2004. Matt has been a CrossFit Affiliate owner since 2007. Through that time he’s helped teams and individuals make it to the CrossFit Games Regional 4 times including a trip to the CrossFit Games. When Matt isn’t coaching he spends time with his family, whom you will also find at the box on a regular basis!

Brittany Yilmaz-Chambers

CrossFit Level 1 Trainer | MSW, LSW, CCTP
Eat To Perform Certified Nutrition Advisor

Co-Owner, Brittany Yilmaz-Chambers has always had a passion for community and connecting with others. Pursuing this passion first through volunteer work, then yoga and cross training during her college career, and later professionally as a social worker, Britt discovered that she could also fulfill that passion in CrossFit. CrossFit quickly captured Britt’s heart and she attained her CrossFit Level 1 Trainer certificate one year after starting CrossFit. Britt strives to share all aspects of CrossFit with those she encounters in hopes of helping members achieve their goals and find the fulfillment offered in CrossFit. With a dedication to holistic healing, clean eating and connecting with the power of God and self, Britt believes fitness is much more than exercise. When Britt’s not coaching, you can find her working with her nutrition and therapy clients, training and spending time with her family and friends.

Loretta Pavie

CrossFit Level 1 Trainer | CrossFit Kids

Retta’s athletic career began in second grade when she picked up a basketball for the first time. While she played softball, field hockey, and lacrosse, basketball was her true love. She played basketball through her freshman year at Kutztown University until injuries forced her to “retire”. Retta’s retirement from playing opened up a new door to begin her coaching career. She coached the Boyertown Lady Bears basketball teams for eight seasons.

While training for her second full marathon in 2014, Retta tried CrossFit for the first time and it quickly became her new passion. She loves the energy and motivation of working out with other members and being challenged physically and mentally every day. Although injuries the past two years have forced her to sit out and scale the wods, her love for the sport has not wavered.

Retta’s goals as a coach at CrossFit Fidelity are to motivate and encourage the members to achieve their goals and help them realize they can accomplish success outside of their comfort zone. Retta also finds much joy in being the CrossFit Kids coach. Her hope is that she can pay it forward to the most important people in the world…the children of our community! Retta also loves organizing events for our box!

Mike King

CrossFit Level 1 Trainer | CrossFit Olympic Lifting Trainer

After years of destroying his knees playing basketball and volleyball Mike King was inspired to try CrossFit in April of 2010. He hasn’t looked back since and now you can find the entire King family at the box. Mike received his Level 1 Trainer Certificate in September in 2012 and again in 2017. Outside of the box Mike is first and foremost a husband to Mindy and a father to Daniel and Hannah. Mike’s goals as a coach are to ensure Proven athletes have fun (safely), achieve their goals, and embody the CrossFit spirit of virtuosity. Ask him about that.

Chris Lebresco

CrossFit Level 1 Trainer

Chris is one of many CrossFit Proven success stories. Back in April of 2013, Chris came to Proven overweight and out of shape. After only 8 months of dedication to CrossFit along with a healthy diet, Chris was able to shed 50lbs and become stronger and healthier than ever before. During this transformation, Chris’ passion for CrossFit grew and now as a coach he is looking to help others reach their fitness goals.

Chris enjoys staying active by running, biking and swimming and frequently competes locally in 5k runs, bike races, triathlons and CrossFit competitions. He also plays basketball, deck hockey and tennis whenever he gets a chance.

Chris’ goal as a CrossFit Trainer is to help CrossFit Proven members take their athletic abilities to the next level and to see members constantly improving.

When Chris isn’t coaching or working out, you can find him taking care of his two children Nick and Brooke and trying to keep up with his CrossFit wife, Lindsay. You may also run into Chris out at your favorite bar or restaurant where he regularly performs as a solo acoustic act throughout the Philadelphia area.

Mike Johnson – “MJ”

CrossFit Level 1 Trainer

MJ has always been active in sports and recreation; from baseball to football and long distance backpacking since the age of 7. He signed himself up (as well as his wife, without her knowledge) at Proven the day after returning home from his honeymoon in June of 2012 and hasn’t slowed down since. The decision to coach at Proven was easy as he gained great knowledge and respect from the sport of CrossFit and sharing that with others is very rewarding to him. A graduate from the University of Pittsburgh with an MBA from Texas A&M, MJ is an accounting manager by day, and lives in Exton with his wife and daughter.

Brian Parks

CrossFit Level 1 Trainer

Brian has been passionate about fitness for over 30 years, including gym memberships, running, adventure racing, golf and other outdoor activities. He is also an avid woodworker and gardener. He found CrossFit through friends in 2011 and was instantly addicted to the workouts, the atmosphere and the community. Brian has a passion for teaching others and is motivated by helping other athletes excel at all aspects of CrossFit. When not at the box, Brian enjoys spending time with his family and can be found watching his daughters compete in equestrian events and field hockey.

Coach V


Coach V has been in the fitness industry for the last 14 years. He is a former obese class II individual that started playing sports at a very early age and never stopped since. He obtained his bachelors and masters degrees in Human Physiology while playing D-1 college football and has been successfully working with athletes at the amateur, collegiate, and semi-pro levels in North America and Europe. He specializes in Strength & Conditioning, behavior/lifestyle modification, and weight loss. When he isn’t coaching or working out at the gym, he is working with individuals all around the world as a remote wellness coach and physiologist for Noom.

Shannon Fitzgerald

CrossFit Level 1 Trainer

From a young age Shannon grew up riding dirt bikes and horses. When she began high school she gained interest in softball and got the opportunity to own her first horse. During this time she searched for something to bring her strength to a new level, and that was Crossfit. She has been in love with this style of fitness since 2012. In college is when she found it extremely rewarding to be able to help others in her box achieve their goals, along with being apart of a new community. There she was encouraged to become a coach and discovered a new found passion. After college she searched for a new community to be apart of, thankfully Crossfit Proven and Fidelity was just that!

Michael Esterlis

CrossFit Level 1 Trainer

Mike is no stranger to fitness, he has been involved in organized sports from the young age of 5! Growing up he played soccer, baseball, and basketball. When he wasn’t playing sports you could find him running. His passion for running led to joining the track team in high school. He then moved on to play collegiate soccer at Penn State Berks. In an effort to fuel his competitive drive Mike began running marathons (yes that is 26.2 miles) in 2005, until he found Crossfit in 2013 with Crossfit Proven. Mike has been a fan and advocate for Crossfit ever since! Being a volunteer firefighter, Crossfit has allowed him to better perform his duties. Today, if Mike isn’t in the gym, or volunteering his time as Assistant Chief at the firehouse, you can find him golfing or skiing. Mike’s favorite aspect of Crossfit is that it is infinitely scale-able and is a place for everyone to tap into their competitive drive.