18 Great Cardio Workouts That Don't Require Running

If you love the long and isolated nature of running, hop on two wheels instead. "Cycling is great because you can change your intensity depending on the terrain you choose," says Herman. "You can go mountain biking, which is more intense and requires bursts or speed, or road cycling, which tends to be more endurance based." If you do go out, make sure you use clip-ons so you work your hamstrings as much as your quads. And plan your route ahead of time. That way if you'll know when a downhill is coming up and push yourself as hard as you can leading up to it.