Mark Leffler - Certified personal trainer located in San Francisco, California.

My name is Mark Leffler and I’m an ACSM Certified Personal Trainer in San Francisco, CA.

I began my career in the fitness industry in the Greater Boston area of Massachusetts in 2009. Since then I have relocated to the west coast, have met some great minds in the industry, and have had the opportunity to work with many people of diverse backgrounds. Learn more

Principles I train by



WTFO believes in shared knowledge and educates clients, during their training, on the scientific disciplines behind an excellent foundation for your best fitness and wellness.



WTFO believes in keeping you healthy. You are encouraged to perform exercises that are beneficial to your health, but challenge your will.


Form and Function

WTFO believes maximum benefits, in strength and mobility, are achieved by aligning your training routine with physical demands encountered on a daily basis.

WTFO reviews

5 star overall rating 16 reviews
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Patricia H. yelp profile picture

Patricia H. says,

5 star overall rating 12/14/2017

Mark is an amazing trainer. My first visit I needed help getting up and down on the mat! Six months later I'm doing straight arm planks! I'm stronger and...

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Atch S. yelp profile picture

Atch S. says,

5 star overall rating 5/22/2017

Bottom-line: All the reviews for Mark are amazing because he's the trainer you want to have. I've worked out with Mark for years and I have no plan to...

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Mike K. yelp profile picture

Mike K. says,

5 star overall rating 10/7/2014

I've been working out with Mark for over a year and a half now, and am really glad I found him. Prior to starting to work with Mark, my workouts were...

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