STAFF

Alisha is a certified personal trainer, nutrition coach, and also the founder of Optimal Health & Nutrition. With a background in structured strength training and performance-based programming, Alisha specializes in strength and nutrition strategies that support muscle retention, metabolic health, and long-term vitality. Her training philosophy blends progressive strength blocks, metabolic conditioning, and accountability-driven coaching. She believes structured progression builds both physical strength and mental resilience. Alisha works with clients of all ages, from youth athletes to adults navigating demanding careers, family life, and hormonal transitions. In addition to one-on-one and small group training, she provides InBody composition analysis and individualized nutrition coaching. As both a coach and entrepreneur, Alisha is passionate about building a community where education, accountability, and support lead to lasting transformation.

ALISHA TSIMBIDAROS - FITNESS DIRECTOR

Jack is an NSCA-CPT certified personal trainer and he’s spent the last 15 years training and developing his craft at the 6S Institute. After 10 years as a dedicated client and member of the 6S community, he transitioned into coaching and has been training clients there for the past five years. Jack specializes in strength and performance training, helping clients build real-world strength, improve athleticism, and train with purpose. His approach is rooted in science-based lifting—smart programming, clean execution, and progressive overload—so progress is measurable and sustainable. He’s especially interested in how technology and AI can enhance training, from better data tracking and recovery insights to more personalized programming decisions. Whether someone is chasing a new personal best, looking to move better and feel stronger, or wants a structured plan they can trust, Jack brings focused coaching, clear progressions, and a performance-minded mindset to every session.

JACK DIRICO - FITNESS COACH

TESTIMONIALS

"Since starting the 6S Institute, I’ve lost over 90lbs, and more importantly, I feel so much better about myself. The routines flow seamlessly and before you know it, the session is over. Great mix of cardio, strength training, core work, and the mental exercises and added stretching and relaxation techniques make it unlike anything else I’ve ever tried. It’s been the most effective fitness program for me."

- Anthony R., Boston, MA

"When our son was at a low point in his sophomore year of high school, we sent him to Mark in hopes he could reinvigorate him. Through challenging, physical, one-on-one workouts, Mark was able to connect with our son and bring him back both mentally and physically. He helped our son gain awareness and perspective of why he was struggling, this combined with the physical training, enabled our son to get back on track. We highly recommend Mark for his excellent work with teenagers."

- Parents of high school student- Boca Raton, FL