"My sister told me about the Power 90 workout tapes [a 90-day, circuit-training boot camp], and I started in March 2003," says Keenan, 26. "Later I did other workout DVDs – Slim in 6, and P90X. When I first started, pull-ups seemed impossible to me; I couldn’t do any. Now I can do 15 in a row. That's an amazing thing."