With more than 3 million copies sold, P90X has been the best-selling home exercise program for seven years in a row and has attracted legions of fans including celebrities, weekend warriors and stay-at-home moms. Since 2004, the now ubiquitous advertisement has inspired viewers with compelling before- and after-P90X photos, moving testimonials from regular folks, and snippets of trainer Tony Horton’s no-nonsense workouts.