Jillian Michaels' Calorie-Burning Workout

Short on time? No problem. This circuit, created for Health by Jillian Michaels, combines strength-training and cardio so you torch major calories while you tone.

"You want to do what is going to be the most effective for your calorie burn and your schedule," she explains. Do each move as many times as you can in 30 seconds, while maintaining good form, then go to the next one. Complete circuit three times, twice a week.

Jillian's key rule: "Don't rest! You shouldn't do a move and then wait to do another one. Go from one move to the next to the next. So while one group of muscles is resting, you've moved on to a different muscle group. If you've done push-ups, do lunges; if you've done lunges, do pull-downs. Keep it moving!"

Lie face up, hands resting lightly on back of head.

Raise legs 3-6 inches; contract abs. Crunch torso up, then rotate it so ribs draw a clockwise circle.

Repeat in opposite direction.

Stand with feet hip-width, a 5- to 8-lb dumbbell in right hand, left hand extended to side at shoulder height

Step out to left as you lower into a squat, and pass dumbbell under left leg to left hand, and around left knee.

In one fluid movement, pass dumbbell under right leg to right hand; continue alternating.

Stand with feet shoulder-width, arms extended to sides at shoulder height, palms down.

Step right leg forward about 2 feet and lower left knee so both knees are at 90 degrees. Twist torso to right and reach right hand back to touch left heel while raising left arm straight up.

Return to start; repeat on opposite side.

Get into "up" part of a push-up; lower chest and bend elbows, stopping at 90 degrees.

Lift right hand and left foot, rotating upper body to the right while bringing left knee across body toward right armpit. Pivot on right foot and continue rotating torso until you're face up. Hands should be directly beneath shoulders and feet hip-width, knees bent at 90 degrees. Lift hips until torso is in tabletop position.

Lift left hand and right foot, rotating upper body to right, pivoting on left foot until you are back in the "up" part of a push-up. Repeat in opposite direction.

Stand with feet slightly wider than hip-width, left arm out to side at shoulder height.

Squat down; place right hand on floor just under center of chest. Squeeze abs and jump feet back into one-arm plank. Jump back toward hands, landing in a squat.

Jump up; return to start.

Come into side plank on right side with core engaged, hips lifted, sides of both feet on floor, right foot in front of left; lift left arm straight up.

Raise right leg as high as you can, then return to floor.