5 Moves Using A Swiss Ball That Will Tone Your Middle And Sculpt Your Thighs In 4 Weeks

This is called the 100 because you will pump your arms and breathe for 100 counts. Place the ball between your ankles right above the ankle joints and squeeze, keeping your legs off the floor. Curl your head, neck, and shoulders off the mat, and start to pump your arms up and down (imagine that you're pressing a rubber ball down beneath the surface of a pool to control your movement and avoid flapping your arms). Inhale for 5 counts and exhale for 5 counts until you've reached "the 100." If you need a modification, bend your knees into tabletop position.

(Got 10 minutes? Then you've got time to lose the weight for good with Prevention's new 10-minute workouts and 10-minute meals. Get Fit in 10: Slim & Strong for Life now!)

Keeping the ball between your ankles, and legs lifted long, place both hands around your right knee and bend it in toward your body while rolling the ball up the left leg. Switch sides with control, and really squeeze those inner thighs to keep the ball in place as you move. Complete 10 sets (or 5 on each side), engaging your core and keeping your head lifted if you can.

MORE: The Only 9 Things You Really Need For Strength Training At Home (And None Cost A Fortune)​

Now you get to play "catch" with yourself—fun! With the ball between your ankles, hug both knees to your chest and curl your upper body up and off the mat. Scoop your core in and extend the legs out long in front of you, arms lifted overhead. Hug those legs back in, take the ball out, hold it between your hands, and extend the arms and legs back out, this time squeezing in on the ball with your arms as you reach overhead. Repeat 10 times, alternating the ball between the ankles and hands each time and stretching as long as you can. (FYI, this is the best stretch to ease your tight, tense back.) 

Place the ball back between your ankles. Lace your hands behind your head with elbows open to the sides, and lift your legs up as straight as you can get them. Use your core to hold your torso up, and try not to pull on your neck. Keep your upper half strong as you start to lower those legs down in front of you—the lower you go, the harder it will be. Make sure you keep squeezing in on the ball, and keep your lower back fully on the floor. With control, lift the legs back up. Repeat.

MORE: 5 No-Equipment Pilates-Inspired Moves You Can Do At Home​

Keep the ball between the ankles and hands behind the head. With legs stretched out, squeeze in on the ball and start to cross the right leg over the left. As you do this, rotate the upper body toward the top leg, and then switch sides. The motion doesn't have to be big, and make sure the rotation of your torso is coming from the ribs and not just your neck. To cross your legs, use your inner thighs and hips, not just the knees. Remember, the lower the legs go, the harder this will be for your core, and the harder you squeeze in on the ball, the more challenging it will be for your inner thighs. Try for 5 times on each side. (Hate crunches? This ab workout is for you.)