Break a sweat by moving and shaking. Simply make a playlist with your favorite "cut a rug" tunes ("Girls Just Want to Have Fun"? "Single Ladies Put a Ring On It)"?), then turn up the volume, and start breaking it down. For even more fun, invite some gal pals over and get grooving (and laughing). The best part is that you'll each burn about 200 to 600 calories per hour. Now that's something to dance about!