About Marcellis
NASM Certified Personal Trainer (CPT)
NASM Performance Enhancement Specialist (PES)
ACE Fitness Nutrition Specialist
Orthopedic Fitness Specialist — MedFit Classroom
Biomechanics Method Corrective Exercise Specialist
B.S. In Business Administration. (University of San Francisco).
Marcellis Shaw is a San Francisco personal trainer with over a decade of experience helping clients build strength, move better, and create lasting fitness habits.
Growing up, Marcellis was always active and passionate about sports — so much so that his dad and family friends nicknamed him the "Sports Encyclopedia" for studying athletics the way other kids watched cartoons. That early obsession with how athletes move and perform laid the foundation for everything that followed.
Though he grew up surrounded by naturally gifted athletes in his family, Marcellis wasn't one of them — and that turned out to be his greatest advantage. It sent him to the gym to figure things out for himself, developing a deep understanding of training from the ground up rather than relying on natural ability.
After college, Marcellis worked as a financial analyst — the classic 9-to-5 — but never stopped training hard and playing basketball after work. Over time, the combination of long hours sitting at a desk, heavy training, and a physical sport caught up with him. Nagging injuries and chronic pain became a regular part of life. Rather than accept it, he dove into research on movement imbalances, corrective exercise, and rehabilitation — and started fixing himself.
That's when it clicked. If he could solve these problems for himself, there were countless others sitting at desks, training hard, and dealing with the same issues who needed the same help. He left the finance world, got certified, and never looked back.
Today Marcellis offers private gym sessions, in-home and workplace training, and online coaching across San Francisco, with specialties in muscle growth, sports performance, weight loss, wedding preparation, pre and postnatal fitness, and orthopedic rehabilitation. He holds certifications from NASM (CPT & Performance Enhancement Specialist), ACE (Fitness Nutrition Specialist), MedFit Classroom (Orthopedic Fitness Specialist), and the Biomechanics Method (Corrective Exercise Specialist).
Whether you're just getting started or pushing toward your next goal, Marcellis builds programs around your life — not the other way around.