You remember doing sprints for high school sports. They hurt—and that's why most of us would do anything to avoid heading to the track. New research from health and fitness expert Phil Cambell, however, shows that anaerobic activities like interval workouts cut more body fat than long aerobic activities like jogging—while increasing lean muscle mass. On top of those benefits, "anaerobic exercise—hard and fast, sprinting types of exercise—is shown to make the body produce significant amounts of anti-aging growth hormone, says Campbell. Now, where's that box jump?