Long Island's Top Personal Trainer

20+ Years

Experience

100+

Clients

Certifications

My Journey

Early Health Transformation

Health and wellness were not priorities during my childhood. By sixth grade, poor nutrition and a sedentary lifestyle had led to obesity and severe deconditioning. Even light physical activity caused significant fatigue, and physical education classes were a source of embarrassment rather than confidence.

At fourteen, I began making deliberate changes to my nutrition and activity habits and enrolled in swimming lessons. The structured training served as a catalyst for change. Within seven months, I lost nearly 30 pounds and experienced a level of energy and physical capability I had never known. As these improvements became evident, my motivation accelerated. The experience shaped my understanding of health — not as an abstract concept, but as something that fundamentally improves quality of life and daily function.

Commitment to Fitness and Professional Development

By age sixteen, I joined a health club and quickly developed a level of strength and conditioning that led peers to seek my guidance. The contrast with my earlier experiences inspired me to pursue fitness professionally, and I became a personal trainer in 2007.

As my career progressed, I pursued formal education and advanced certifications to deepen my understanding of the science underlying health, performance, and chronic disease prevention. I earned a Bachelor of Science in Health Science, with academic training that included Environmental Health & Safety principles, and obtained multiple certifications in personal training and nutrition. This education broadened my ability to work safely and eﬀectively with diverse populations while emphasizing risk reduction and long-term health outcomes.

This progression led to my current role as an Exercise Physiologist at a national laboratory, where performance, safety, and long-term health outcomes are essential.

Keith Serin - Long Island Personal Trainer

Coaching Focus & Expertise

Over the past 18+ years, I have coached a diverse population in both gym and in-home settings.

My work has focused on:

weight management and metabolic health
strength and conditioning
mobility and injury prevention
return-to-activity programming
long-term habit development

While I have helped clients achieve a wide range of goals, I find the greatest professional fulfillment in working with older adults and individuals managing chronic health conditions such as obesity, cardiovascular disease, and mobility limitations. Helping clients change the trajectory of their health remains the central focus of my work.

Purpose Beyond the Gym

Training has also enabled me to pursue demanding outdoor activities includin mountaineering, trail running, rock climbing, snowboarding, whitewater rafting obstacle course racing, and scuba diving. These pursuits reinforce a practical goal of fitness: building strength, endurance, and resilience for an active life that includes a wide range of physical activities.

I aim to help clients develop the same sense of purpose — training not merely for appearance, but to maintain the strength, stamina, and mobility needed to fully participate in the activities they enjoy.