Trade Slow Cardio for Interval Training

The road to a leaner body isn't a long, slow march. It's bursts of high-intensity effort paired with slower, recovery efforts. Fifteen to 20 minutes of interval training performed like this can burn as many calories as an hour of traditional, steady-state cardio. And unlike the slow stuff, intervals can keep your body burning long after the workout ends.

http://www.intervaltraining.net/