Start in plank position with feet hip-width apart and hands wider than shoulders. Keeping core tight, lower chest toward the ground, then push through palms to return to plank. Inhale as you lower, exhale as you push.

A. Stand with feet hip-width apart and place hands on head, elbows pointing out. Lower into a squat until thighs are parallel to floor.

B. Lower right knee to the floor.

C. Lower left knee to the floor.

D. Step right foot forward, knee bent at a 90-degree angle. Step left foot forward to return to starting squat position. That's one rep. Repeat, alternating the starting foot.

Lying on your stomach, lift your legs and arms off the floor, arms straight in front of you. You should be squeezing your glutes to keep your legs up. Pull your elbows down to your waist, return to starting posting, and repeat.

Lie on your back with arms extended overhead, palms facing up. Curl up as you raise straight left leg, reaching to tap toes or shins (or as far as you can go). Slowly lower to start. Switch sides, reaching for right leg. That's one rep.

Start in a high palm plank, then bring left foot to the outside of left hand. Immediately jump-switch left foot back to plank and right foot to outside of right hand [shown]. Continue quickly alternating sides.

A. Start in plank with left palm on floor in front of chest, fingertips pointing right, and right palm in front of left, fingertips pointing left.

B. Bend elbows to lower body until forearms touch floor. Push body up. That’s 1 rep.

Form tip: This move is very challenging, so drop to your knees to modify it if you need to, says Jillian Michaels.

A. Stand with feet hip-width apart and arms by sides. Step right leg back into a reverse lunge, bending both legs 90 degrees, bend right arm forward and bend left arm back.

B. Push through left foot to come to standing, kicking right leg in front of you, switching arms as you do it. Return to starting position and continue for 30 seconds. Switch sides; repeat.

Standing, hinge at your hips, bringing torso nearly parallel to the floor. Bend elbow as you create a "hugging shape" with your arms, hands meeting in front of you. Pull up and back as you bring elbows behind you, squeezing your back. Repeat.

Lie on your back with your hands behind your head, keeping your legs straight. Bring one leg into the air while the other hovers parallel to the ground. Switch legs quickly and continuously for one minute.

A. Stand with feet hip-width apart, elbows bent. Squat, then jump high, swinging arms open and slightly behind you, landing with soft knees. Repeat for a total of 5 reps.

B. Throw a right cross (punch right fist across your body, pivoting on right foot), then a left jab (quick punch-snap left fist forward). That's 1 rep. Do 10 reps of the cross-jab combo. Repeat the 5 jump squats and 10 reps of cross-jab combo until 30 seconds are up. During next round, perform cross-jabs on the opposite side (cross with left fist, jab with right).

A. Stand a few feet away from the corner of two walls. Lean forward and place left hand on the wall, heels slightly lifted. Put right hand behind back, palm facing away from you.

B. Bend left elbow. Push up to starting position and repeat.

Form tip: A corner gives you a bigger range of motion, but if you don’t have one in your room, just don’t bend your elbow as much.

A. Stand with feet hip-width apart, hands clasped in front of your chest, elbows bent by your sides.

B. Staying in the squat, extend left leg out to the side and tap toe to floor. Return to starting position, then repeat on the opposite side. That's one rep.

Sit on with legs extended and together and palms pressing into floor behind hips with fingertips facing forward. Push hands and heels into floor to lift hips until body forms a straight line from shoulders to heels. Return to start.

Start on floor in side plank position, body balancing on left palm and sides of feet, right foot staggered in front of left; bend right elbow and place palm behind ear. Rotate torso to bring right elbow up to touch inside of left elbow. Reverse motion back to starting position to complete 1 rep. Switch sides; repeat.

A. Stand with feet hip-width apart and arms by sides. Crouch, plant palms on floor, then jump feet back to plank position.

B. Lower chest and thighs to floor, then push up to plank.

C. Hop feet toward hands, then jump up, clapping hands over head.

Place hands shoulder-width on floor, rotate arms so elbows are pointing backward. Lower chest to hover just above the floor, elbows skimming the sides of your ribs, then push through palms to return to plank. Inhale as you lower, exhale as you push. (Drop to knees for an easier variation.)

A. Lunge with left leg forward.

B. Keep left foot planted, then pivot on right foot, rotating torso 90 degrees and turning toes out to come into a wide sumo squat. Keeping right foot planted, pivot on left foot to rotate into a lunge with right leg forward. Return to sumo squat. That's 1 rep. .

Standing, reach both arms up overhead before pulling elbows down and out to your sides, creating your own resistance as you mimic a pull-up movement. Bring arms back up to starting position, and repeat. Elbows should remain pointed toward the floor with back and core engaged.

A. Start in forearm plank with palms facing up and with each foot on a Slidez disc. (No disc? No problem. Use paper plates on carpet or towels on a hard floor.)

B. Keeping body in a straight line, press forearms into floor (forearms will not move) to push body backward so arms form a 60-degree angle (or as wide an angle as you can maintain comfortably). Reverse the motion by pressing into forearms to pull body forward to starting position.

A. Run in place with high knees, pumping arms for 4 seconds. In one fluid motion, crouch, place palms on floor, jump feet back to plank and lower entire body to floor.

B. Then quickly press up and jump feet to hands; stand and immediately start running in place again. Continue alternating running and sprawling for 30 seconds.

A. Start in high palm-plank position. Do 1 push-up.

B. Lower knees and come up to kneeling, then quickly press arms overhead with palms facing up.

A. Stand with feet hip-width apart, toes turned out, and arms by sides. Squat until butt is hovering above heels, hands clasped together with arms straight in front of chest to start.

B. Jump as high as you can. Land in start position. Form tip: Skip the jump to make it easier.

Start in high palm-plank position. Lift right leg directly up off floor. When balanced, lift left hand off floor and extend arm straight forward at shoulder height with palm facing down. Return to start. Switch sides; repeat.

A. Sit on floor with legs extended and palms pressing into floor behind hips with fingertips facing forward. Lift straight legs off floor, bending elbows and rolling onto tailbone. Without moving your torso, bend knees in toward chest.

B. Extend legs straight out toward left. Return to start, then extend legs toward right. That’s 1 rep.

A. Stand with feet hip-width apart, arms at sides. Crouch, place palms on floor, jump feet back to plank.

B. Lower body to floor, then explosively push up and jump feet to hands to land in a staggered stance with left foot forward, knees and elbows bent as if balancing on a surfboard.

C. Jump, tucking knees toward chest and bringing palms over knees. Land softly to complete 1 rep. Repeat, this time landing with right foot forward.

Start in plank position with hands wider than shoulder-width. Lower chest toward floor in a regular wide-grip push-up. Then bend knees and shift hips back so knees are 2 inches off floor and arms are extended. Lift hips up into downward dog position. Then tucking tailbone and rounding spine, roll back into plank position.

A. Stand with feet hip-width apart, hands clasped in front of your chest, elbows bent by your sides.

B. Staying in the squat, extend left leg out to the side and tap toe to floor. Return to starting position, then repeat on the opposite side. That's one rep.

A. Stand tall with your feet shoulder-width apart. Place your hands on the back of your head, keeping a tight core and upright torso.

B. Bend forward at the hips, lower your torso until you feel a stretch in the hamstrings or until your back is almost parallel with the ground. Raise to return to the starting position.

Form tip: The movement should come from your hips, and back should be flat throughout the movement. Squeeze your glutes at the top.

Start on floor in forearm plank position, body balancing on forearms and toes, palms flat. Keep hips level and bend right knee out to side toward right triceps. Return to plank. Switch sides and repeat to complete 1 rep.

Lower your body into a squat. Place your hands on the floor directly in front of your feet. Jump your feet back with only one foot touching the floor. Bring your feet back to your hands, then jump into the air on that same foot. Repeat for 30 seconds on one leg, then switch to the other leg for the next round.