7 Ways to Get a Better Body in 30 Minutes or Less

ACE found that a 20-minute kettlebell routine that involved swinging the weight while lunging, squatting and reaching burned at least 20.2 calories per minute—which even the study authors admitted was "off the charts." They determined that a well-executed kettlebell routine can be as effective as running at a six-minute-mile pace and then lifting weights. Note: The reason this workout clocks in at 30 minutes instead of 20 is that a dynamic warm-up is non-negotiable: As Jessica Matthews notes, you shouldn't go swinging 15 pounds over your head and between your knees when your muscles are stiff (the ACE study also included a five-minute cooldown, which Matthews recommends for injury prevention).

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