Shaun Zetlin has run his own personal training business in New York City for more than 10 years. A graduate of the University of Delaware, he holds certifications from the National Academy of Sports Medicine (NASM) and the International Sports Sciences Association (ISSA). His work has been featured in books, magazines, websites, television, and radio, including Demos Medical, Prevention, Price World Publishing, Conde Nast, Livestrong, the FX channel, and Discovery Channel with Dr. John Whyte. His book 'Push-up Progression Workout for a Stronger Core' is currently in paperback and e-book format, and the 2nd edition became available in January 2015.