Alternating high- and low-intensity intervals not only eases boredom but it also burns more fat in less time. "You can get better benefits within a shorter time," says Cloutier. In addition to burning more calories during your workout, some studies suggest you can keep burning calories for up to 16 hours afterward! It’s the result of a process called EPOC (excess post oxygen consumption). You've felt this effect if you're ever taken a shower after a vigorous workout and continued to sweat. "Bringing your body back to its baseline [pre-workout metabolism] takes extra calories," says Cloutier. Even beginners can practice this principle: Alternate between a brisk and slow pace when you’re walking. Or, try alternating walking with a few stair climbs.