As anyone who's ever stepped onto a treadmill can tell you, a cardio routine is like a razor: After a few weeks of constant use, it becomes dull and ineffective. There's no better time than the summer, when the world can be your gym, to infuse it with new energy--and burn fat and boost endurance at the same time.
Ready for a new challenge? Here are three outdoor workouts for wherever your summer takes you. And don't forget: You can get more cool exercises, innovative workouts, and fast fitness fixes by signing up for our free Exercise of the Week newsletter.