Keep it short

Usually work out for 30 minutes? Exercise for a third of that—but go hard! "An intense 10 minutes jump-starts your metabolic furnace and equals about 20 or 30 minutes at a moderate intensity," says Jordan Metzl, MD, author of Dr. Jordan Metzl’s Workout Prescription. If you can’t spare the full 10 minutes, you can sweat for even less time: According to a 2013 study from Colorado State University, exercising for just 2 ½ minutes at a high intensity (think running or biking sprints) can help you burn 200 more calories over the rest of the day.