Talk about a catch-22: Doing something healthy, like eating a low-cal meal, can make you less likely to exercise and more likely to gorge yourself with food later on. This is because of a phenomenon scientists call licensing, which happens when we feel that we've earned the right to be self-indulgent. Most people have a tendency to want to balance things out, says Kathleen Vohs, Ph.D., an associate professor of marketing at the Carlson School of Management at the University of Minnesota. So when we do one thing that's good for our health, which often requires exerting plenty of discipline and self-control, we like to follow it up with something that lets us indulge ourselves.
What does a HIIT workout look like? You could jog for two minutes, sprint for one minute, jog for two minutes, sprint for one minute. Or you could do a HIIT workout on a bike, or by running up stairs and then jogging back down. The key is that you go relatively all out for a short period of time, then recover by maintaining a moderate level of intensity, then go again. 
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