12,000+ Sessions • 107+ Clients • South Bay Area
Move Better.
Feel Stronger.
Live Longer.
Hi, I'm Jeffrey Sun, a personal trainer in San Jose serving the South Bay Area. I help busy professionals eliminate pain, build functional strength, and train for health longevity - not just quick fixes.
Testimonials
What Clients Say
Structured Health Lifestyle
“My body feels like a well-oiled machine and I feel stronger than ever before. Jeff makes the entire journey very enjoyable. He has been the best investment in my fitness journey and I highly recommend him.”
Sneha
Pain Free & Functional Strength
“I originally only planned to do sessions for a few months, and now it's been 4 years. Sessions with Jeff are really great and I'd recommend them to anyone.”
Marshall
Achieved Dream Weight
“He made things seem doable rather than overwhelming. Jeff is incredibly easy to work with and he's truly become a friend. With his help, I've achieved my goal weight and I'm still going strong.”
Cristina
Discipline and Strength Building
“Before working with Jeff, I was never disciplined. Now, it has changed significantly for my workouts and diet. Thank you Jeff, thank you for everything.”
Kanth
Consistency and Health Longevity
“Working with Jeff completely changed the way that I train. His programs have helped me stay consistent for over 3 years. I would highly recommend working with Jeff.”
Josh
Cured Neck and Low Back Pain
“Jeff helps me move out of my comfort zone. He really understands what I would like to achieve.”
Chen
Flexibility and Strength
“Jeff is very detail oriented. The workouts were much more fun and I saw a lot of results. He was able to balance out my body and keep me consistent.”
Curtis
Functional Strength for Life
“Before Jeff, I went to the gym once a week. After, I consistently go to the gym twice a week. My strength has gotten a lot better and my body has gotten a lot more toned.”
Karson
Sound familiar?
Are You Tired Of…
Constant neck and upper back tightness from desk jobs
Low back pain from a sedentary lifestyle
Lack of structure and routine in exercise and health
Never learning proper form or getting formal instruction
Wanting to feel strong and capable in your body again
What might sound too good to be true is totally achievable with the right system.
That's why I created a training approach focused on health longevity — not quick fixes that don't last.
Start Your TransformationProcess
How It Works
A simple, proven process to help you move better, feel stronger, and build a body that lasts.
Free Consultation
Book a free 1-hour consultation where we discuss your goals, assess your current fitness level, and identify any pain points or limitations. This includes a short workout focusing on breathwork, abs, and mobility.
Custom Program Design
Based on your consultation, I create a personalized training program tailored to your goals, schedule, and body. We'll set up progress tracking through my app and schedule a DEXA scan for baseline measurements.
Training Sessions
Work with me through in-person sessions in the South Bay area or online. Each session is focused on proper form, progressive overload, and building sustainable habits. Most clients train 2-3x per week.
Track & Optimize
Monitor your progress through the training app, regular check-ins, and periodic DEXA scans. We adjust your program as you improve, ensuring continuous progress toward your longevity goals.
Get started
Book Your Free Consultation
Fill out the form and I'll reach out to schedule your free 1-hour consultation. No commitment required.
Plus: Get a free mobility assessment + 1-week plan
Good fit
This Is For You If…
Working professionals in their 20s and 30s
Who want to invest in their long-term health and have the discipline to show up consistently.
People recovering from injury
Looking to transition from physical therapy back to full training safely and effectively.
Those experiencing chronic pain
Neck pain, back pain, shoulder issues - who want to address the root cause, not just mask symptoms.
Athletes and active individuals
Who want to improve performance, prevent injuries, and move more efficiently.
Health-conscious individuals
Who understand that investing in their body now pays dividends for decades to come.
Not a fit
This Is NOT For You If…
- Quick-fix seekers focused only on a number on the scale
- Those looking for crash diets or unsustainable programs
- People who can't commit to consistent training
My Philosophy
I believe in training for health longevity. That means building a body that serves you well not just today, but for the next 30, 40, 50+ years.
If you're looking for someone to help you lose 20 pounds in a month, I'm not your guy. But if you want to build sustainable strength, eliminate pain, and feel capable in your body for decades to come — let's talk.
About
Meet Your Coach
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sessions delivered
Jeffrey Sun
ACE Certified Personal Trainer | B.S. Human Biology
As a certified personal trainer with a degree in Human Biology, I specialize in helping busy professionals in their 20s and 30s build bodies that last. My approach is rooted in physiology and focused on health longevity - not crash diets or unsustainable programs.
With my background as an EMT and athletic trainer, I understand the body at a deeper level. I've seen what happens when people neglect their health, and I'm here to make sure that doesn't happen to you. Based in the South Bay Area, I train clients from San Jose, Sunnyvale, Cupertino, Santa Clara, and Mountain View - both in-person and online.
Specialties
Education
- B.S. Human Biology - UC Santa Cruz
- ACE Certified Personal Trainer
- Division III Athletic Training Internship
- CPR/AED Certified
Experience
- 12,000+ training sessions delivered
- Former Youth Gymnastics and Soccer Coach
- Former Emergency Medical Technician
FAQ
Common Questions
Everything you need to know before getting started.
Still have questions?
jeff@sunfm.fitnessI offer both in-person and online training. In-person sessions are held in Sunnyvale, with clients coming from San Jose, Cupertino, Santa Clara, Mountain View, Campbell, and throughout the South Bay Area. Online sessions are conducted via video call and are just as effective for most clients.