What if I told you I had a magic pill that would boost your metabolism, making you burn fat faster? You’d take it in a heartbeat, wouldn’t you? Well, guess what: I do have that magic pill. And here’s more good news: It’s free! The magic pill I’m talking about is—you guessed it—exercise.

Doctors often downplay the fat-burning power of exercise, because most of them believe in the old calories-in, calories-out rule. And it’s true that the immediate effects of exercise aren’t going to tip the scale very much. For instance, it takes more than an hour of strenuous exercise to burn off a 300-calorie doughnut.

However, that’s just what exercise does in the short run. Here’s what it does in the long run:

• Exercise keeps your metabolism high even after you finish. When you do high-intensity exercise, your muscles experience wear-and-tear (in a good way). After you’re done, your body needs to repair and replenish those muscles—and that takes work. So long after you exercise, your metabolism stays ramped up.

• Exercise builds muscle. Muscle burns more calories than fat—so the more lean muscle mass you create through exercise, the more fat you’ll burn all day long.

The key here is to do the most effective types of exercise.

I’m a huge fan of all kinds of exercise—whether it’s walking the dog, dancing a samba, or playing Twister with your kids—but from a metabolic point of view, some forms of exercise are more powerful than others. Here are two of the best when it comes to melting off that fat:

• Weightlifting. When you lift the heaviest weights you can lift with good form, and do as many repetitions as you can, you’ll get a fantastic after-workout “burn” and build beautiful lean muscle. (As a bonus, lifting weights sculpts your body, so you automatically look slimmer. I call it “rearranging the furniture.”)

• High-Intensity Interval Training (HIIT). In HIIT, you exercise very strenuously in short bursts with periods of less intense exercise in between—for instance, alternating sprinting with walking. Your body needs to work hard during the strenuous stages and the recovery phases, and this really revs up your metabolism. (If you’re very athletic, consider trying Tabata, a more strenuous form of HIIT.)

In addition to incorporating these two types of exercise into your routine, here are three more tips for getting the biggest metabolic boost from your workouts:

• Exercise inefficiently. No, that’s not a typo! People look at me funny when I tell them to make their exercise routine more inefficient, but there’s a good reason for this. When you do the same exercises every week, your routine gets easier, so you burn less fat. Change things up, and your body has to work harder. So surprise your body by switching from hand weights to kettlebells, or from sprinting to swimming.

• Go for quality, not quantity. Stop killing yourself with long exercise routines. Twenty minutes of intensive weightlifting or HIIT training will give you more metabolic payoff than an hour of jogging.

• Exercise regularly. Schedule a minimum of four 20-minute workouts a week. (Take a one-day break between weightlifting sessions, to give your muscles time to recover.) If you find that you don’t have time for that much exercise, make the time—even if it means getting rid of other commitments in your life. Make your health and weight loss a top priority.

Finally, supplement your exercise routines with fun activities that you love, whether it’s bowling, swimming, hiking, yoga, or ballet. All forms of movement will boost your metabolism more than sitting on the sofa—so on the days when you don’t work out, put your body in motion in ways that make you and your metabolism happy!

Keep thinking BIG and living BOLD!