Intense 9-Minute Cardio Workout (Video)

Treadmills and ellipticals can be boring -- and that's not the only problem. You also have to spend a fair amount of time with a machine to get a good workout. Not so with this nine-minute cardio blast. Consisting of jumping squats, side-to-side push-ups, towel rows, towel squats and raises and half-burpees, the intense workout requires no equipment except a towel and will get your heart rate way up.