This website (from bodyrock.tv), explains how to become a bodyrocker - A person who does intense short workouts at home for free (which is a new fitness movement). I love this fitness idea because the workouts are short (which means you don't have an excuse not to do them), but they burn as much calories as if you were to go to the gym and kind-of workout for 1.5 hrs. CHECK IT OUT!!!
4 minute workout burns as many calories as a 40-60 minutes run. Increases metabolism for up to the next 36 hrs. --> Squat thrusts, mountain climbers, high knees, jumping jacks. Do 20 seconds of each exercise as hard/fast as you can, then rest 10 seconds. Do two rounds of this.