Back in the day, you needed a fit friend or a hired personal trainer to get your butt moving at the gym. But now there are apps that'll do that for you (no whining friend or angry buff trainer necessary). Since we're all on our smartphones all the time anyway, you might as well do something useful with these new apps: keeping track of your workout routine, finding new workouts to keep things interesting, and even motivating you to work harder. There are fitness apps for "the only cardio I do is shopping" types as well as the bench-pressing gym buffs. And you really don't have an excuse, because we've found the best of the best for both iPhones and Androids.