About Rochester School of Fitness
We started with a belief: that the right exercise — done right, with the right support — can change what’s possible for people living with chronic conditions, navigating aging, or trying to finally take their health seriously.
RSF has been featured in local television and media coverage for its work with medically complex populations.
Our Story
Rochester School of Fitness was founded in 2006 by Mido Zelenjakovic, a certified clinical exercise specialist, and Dr. Cathy Hahn, a pediatrician. They came from different corners of healthcare, but they shared the same frustration: people with chronic conditions weren’t getting the exercise support they needed, and the fitness industry wasn’t equipped to provide it.
The traditional gym model — drop-in memberships, generic programming, no medical context — wasn’t built for someone managing Parkinson’s disease, recovering from cancer treatment, navigating type 2 diabetes, or trying to stay independent at 78. RSF was built for exactly those people.
Nearly two decades later, that mission hasn’t changed. RSF is a medical fitness and wellness organization in East Rochester, NY — a place where the work is individualized, the staff understands the research, and the program is built around who you actually are and what you’re actually managing.
What Makes RSF Different
This is not a gym with a medical-sounding name. It’s a clinical fitness environment built around individualized assessment, evidence-based programming, and genuine partnership with healthcare providers.
Your Program Is Built Around You
Every RSF program begins with a comprehensive assessment — your health history, your goals, your current mobility, balance, and strength. We don’t hand you a template. We build something specific to where you are right now and where you want to go.
Chronic Disease Is Our Specialty
We specialize in exercise programming for people living with Parkinson’s disease, cancer survivorship, cardiovascular and metabolic conditions, type 2 diabetes, arthritis, osteoporosis, stroke recovery, multiple sclerosis, and peripheral neuropathy — as well as healthy aging and fall prevention for adults at every stage.
We Work Alongside Your Care Team
With appropriate patient authorization, RSF collaborates with physicians, physical therapists, oncologists, neurologists, and other providers. We complement — and never replace — the medical and rehabilitative care your providers deliver. We fill the gap that exists between what happens in a clinical setting and what happens the rest of the week.
Evidence-Based, Not Trend-Based
Our programming draws on current research in exercise physiology, behavioral science, and clinical fitness. We study what the science says about neuroplasticity, sarcopenia, insulin sensitivity, VO2 max, and the specific mechanisms by which exercise affects each condition we serve — and we apply it directly to your program.
Our Team
The people at RSF bring deep expertise, genuine empathy, and a commitment to meeting every person exactly where they are.
Mido Zelenjakovic — Co-Founder & Clinical Exercise Specialist
Mido has spent nearly 20 years building individualized exercise programs for people who need more than a generic workout. His focus has always been the people that most fitness professionals aren’t trained to serve: someone with Parkinson’s disease trying to stay strong enough to stay independent; a cancer survivor rebuilding their body after treatment; an older adult who fell once and is terrified of falling again.
His approach is grounded in exercise physiology, behavioral science, and a fundamental belief in each person’s capacity to change — regardless of age, diagnosis, or how long they’ve been inactive. He’s not a trainer who motivates through intensity. He’s a specialist who meets people where they are and moves them forward from there.
- ✓ B.S. Exercise Science — SUNY Brockport, Exercise Physiology concentration
- ✓ Certified Clinical Exercise Specialist
- ✓ MedFit Education Foundation — Medical Fitness Specialist
- ✓ MedFit Education Foundation — Adaptive Fitness Specialist
- ✓ MedFit Education Foundation — Geriatric Fitness & Lifestyle Specialist
- ✓ MedFit Education Foundation — Certified Nutrition Coach
Dr. Cathy Hahn — Co-Founder & Medical Advisor
Dr. Cathy Hahn is a pediatrician who co-founded RSF with Mido because she understood something important: exercise is medicine, and it works best when it’s prescribed with the same precision as any other treatment. Her medical perspective has shaped RSF’s foundational philosophy from the beginning — a commitment to individualized, medically informed programming that takes each person’s full clinical picture into account.
Dr. Hahn’s involvement ensures that the bridge between medical care and fitness stays meaningful. RSF doesn’t operate in isolation from the healthcare system — it was designed to work alongside it.
Marissa Hartman — Exercise Specialist
Marissa came to RSF because she believes in something that gets lost in most fitness environments: sustainable change has to start with the whole person. Not just their fitness goals, but their life, their habits, their motivations, and the barriers that have gotten in the way before.
She brings energy, warmth, and genuine curiosity to every session — the kind of presence that makes people feel seen and supported rather than judged or pushed. Her goal is not to fix you. It’s to work alongside you until you no longer need the same kind of support, because you’ve built something that belongs to you.
Outside of RSF, she stays active through soccer, running, and time outdoors — a personal commitment to the lifestyle she helps her clients build.
- ✓ B.S. Exercise Science — SUNY Brockport, Health Promotion concentration
- ✓ First Aid Certified
The right place to start is a conversation.
A free assessment is where we learn about you — your health history, your goals, what’s worked before, and what hasn’t. No commitment, no pressure. Just an honest conversation about what’s possible.
Rochester School of Fitness provides general educational information and community-based exercise and wellness services. We do not diagnose medical conditions, prescribe medication, or provide physical therapy or other medical care. Always consult your healthcare provider regarding your medical care.