Celebrity trainer Gunnar Peterson is almost as famous as his A-list clients, and while he's best known for whipping starlets into butt-kicking shape for action films, he's not all Hollywood all the time. Peterson loves helping people find personalized health and fitness programs to fit their unique needs and goals. His no-nonsense style and cheeky sense of humor on Twitter will have you smiling all the way to the gym. Plus, he's not shy about sharing on-the-job anecdotes (Hello, Kardasians!).
Why you'll love him: "What is the most effective and least expensive way to measure body fat percentage? Ask a true friend if you're fat."