David Kirsch may train celebrities like Jennifer Lopez, Britney Spears, and Heidi Klum, but thanks to the power of the Internet, we like to think he's our trainer, too. Kirsch regularly posts his ...

Celebrity trainer David Kirsch shares how to do the super-challenging move he has famous clients like J.Lo, Kate Upton and Heidi Klum do to tone their core, arms, and chest. “This is a pretty ...

The singer maintains an intense workout workout and healthy eating habits to stay fit. The key to J.Lo's booty? Sumo lunges, according to trainer David Kirsch. While other celebrities were posting BTS ...