When it comes to high-intensity interval training (HIIT), the pros definitely outweigh the cons.  While it may feel unpleasant to push your body to go faster and harder for that short time period, the rewards are worth it:  HIIT helps you blast more belly fat, save time, and burn way more calories than a lower-intensity workout alone.  A new study published in the American College of Sports Medicine's Health and Fitness Journal found that a few minutes of training at almost your max can accomplish all of this in way less time than a traditional workout.  How much less?  Try just seven minutes total.  The ACSM's interval workout consists of 12 exercises, which should be done at an intensity of 8 on a scale of 10;  each exercise lasts 30 seconds, with a 10-second rest in between.  Repeat the circuit if you'd like a longer workout.  Keeping the intensity up — and the rest periods short — is key, so click through to learn the moves and then get going!  You'll need a mat and a chair or bench.

1. Jumping Jacks

Warm up your body with a vigorous stint of jumping jacks.  Do these for a total of 30 seconds.

2. Wall Sit

• Stand with your back against a wall, placing your feet about two feet out in front of you.  Feet should be hip-distance apart.
• Bending your knees, slide your back down the wall until your knees are at 90-degree angles.  Your knee joints should be over your ankle joints, so you may need to inch your feet further from the wall to create proper alignment.  Don't let your knees fall in on the midline of your body, or sway outwards.
• Hold for 30 seconds.

3. Push-Up

• Start in a plank position, with palms spread out evenly and your shoulders over your wrists and legs out behind you.  Pull your belly button in and keep your back straight.
• As you lower and exhale, bend your elbows outward to the sides.  Hold at the bottom before you raise back up.
• Do as many reps as possible in 30 seconds.

4. Crunches

• Sit on your mat and bend your knees, planting your feet on the floor.  Put your palms behind your ears.
• As you exhale, pull your abs in and lift your upper body.  Inhale as you lower back down.
• Keep your chin down to keep your neck from straining, and make sure your ribs are aligned with your hips.
• Do as many reps as you can in 30 seconds.

5. Chair Step-Ups

• Find a step, a bench, or a sturdy chair that when you place your foot squarely on it your knee is at a 90-degree angle or larger.
• Step up 20 times leading with the right foot, then the left, bringing both feet completely onto the bench.  To return to the starting position, lead with the right foot to step down to the floor, then the left, until ending with both feet on the ground.  Switch legs and start stepping with the left foot for 20 steps.
• To make this move more challenging, start by stepping onto the bench with your right foot, bring your left foot up and tap the bench with your left toes, then lower your left foot down to tap the floor (as shown).  This is one rep.  Your right foot never moves as you bend and straighten your right knee.This works best on a step or bench, something lower than a chair.
• Repeat either move for a total of 30 seconds.

6. Squat

• Stand with your head facing forward and your chest held up and out.
• Place your feet shoulder-width apart or slightly wider.  Extend your hands straight out in front of you to help keep your balance.  Sit back and down like you're sitting into an imaginary chair.  Make sure your head stays facing forward, not down (focus on something in front of you to help) and that your upper body faces forward as well, bent slightly forward.  Rather than allowing your back to round, let your lower back arch slightly as you descend.
• Lower down so your thighs are as parallel to the floor as possible, keeping your knees over your ankles.  Press your weight back into your heels.
• Keep your body tight, and push through your heels to bring yourself back to the starting position.

7. Triceps Dips

• Position your hands shoulder width apart on a secured bench or stable chair.
• Move your bum in front of the bench with your legs bent and feet placed about hip width apart on the floor.
• Straighten out your arms and keep a little bend in your elbows in order to always keep tension on your triceps and off your elbow joints.
• Now slowly bend at your elbows and lower your upper body down towards the floor until your arms are at about a 90-degree angle.  Be sure to keep your back close to the bench.
• Once you reach the bottom of the movement, slowly press off with your hands, and push yourself straight back up to the starting position.
• Repeat as many times as you can for 30 seconds.

8. Plank

• Lie face down on the floor or face your mat on your knees.  Place your palms so that your shoulders are aligned with your wrists close to your head.
• Push off the floor, raising up off your knees onto your toes and spreading your fingers and pressing down with your palms.  You can also try resting on your forearms as shown.
• Contract your abdominals and pull your belly button in to keep yourself up and prevent your booty from sticking up.
• Keep your back flat and hold for 30 seconds.

9. High Knees/Running in Place

Time for more cardio.  March (also called high knees) or run in place for 30 seconds.

10. Lunge

• Keep your upper body straight, with your shoulders back and relaxed and chin up (pick a point to stare at in front of you so you don't keep looking down).  Always engage your core.
• Step forward with one leg, lowering your hips until both knees are bent at about a 90-degree angle.  Make sure your front knee is directly above your ankle, not pushed out too far, and make sure your other knee doesn't touch the floor.  Keep the weight in your heels as you push back up to the starting position.
• Repeat for a total of 30 seconds.

11. Push-Up Rotation

• Start in a plank position, with palms spread out evenly and your shoulders over your wrists and legs out behind you.  Pull your belly button in and keep your back straight.
• As you lower and exhale, bend your elbows outward to the sides.  Hold at the bottom for one breath.
• Raise back up to top push-up position.  As you reach the top, keep moving in a fluid motion to side plank position:  release your left arm and raise it to the ceiling, keeping your body in a long diagonal line.  Hold for one breath, then move back into push-up position.
• Repeat as many as you can, alternating which arm you are raising, for 30 seconds.

12. Side Plank

• Begin in a plank position (the top of a push-up) and roll over to your left side and plant your left heel down so you are balancing on the outside edge of your left foot.  Stack your right foot on top of your left.  If this is too hard, bend your left knee and place your left foot flat on the ground in front of your right leg for support.
• Keep your right arm on your side as shown or reach it straight up toward the ceiling to lift your waist even more.
• Press your left fingertips into the floor to take pressure out of your wrist.
• Hold for 30 seconds.