It's small but packs a big punch. A medicine ball is a weighted ball used to whip your body into shape, without taking up much space. It's similar to standard weights, but with the medicine ball you only need one to get in a full workout. If you're a fitness newbie, start with a 4-pounder (sold at most sports stores). Advanced fitness junkies may choose to use a 20-pound ball.

Dr. Rick Kattouf, author of "Forever Fit," is a triathlon and conditioning coach based in South Carolina. Here he shares his favorite medicine ball exercises. Do each exercise 10 times. Gradually work up to doing each one 25 times.

Squat to shoulder press

Beginning in a standing position, hold the medicine ball at chest level. Squat, trying to drop your buttocks as low as possible, keeping your heels on the ground. Then, stand up and raise the medicine ball directly over your head. Bring the medicine ball back to your chest and repeat.

Muscles worked: quadriceps, glutes, triceps, shoulders

Jump squats

Stand and hold the medicine ball at chest level. Squat as low as possible while keeping your heels on the ground. Jump off the ground as high as you can. When you land, you want to immediately drop back into the squat position. This is designed to be a very fast-paced, rapid-fire exercise.

Muscles worked: quadriceps, glutes

Straight-leg dead lift

In a standing position, lift the medicine ball above your head, keeping your arms extended. Bend forward from your waist as if you are trying to touch your toes. As you bend forward, keep your arms extended while holding the medicine ball and bringing the ball toward your feet. Keep your knees slightly bent the entire time. When the ball hits your feet or the floor, return to your original standing position, maintaining the full extension of your arms overhead.

Muscles worked: hamstrings, shoulders

Sit-up chest press

Lying on a mat or a rug on your back, knees bent and feet flat on the floor, hold the medicine ball on your chest. Perform a sit-up. As you get toward the top of your sit-up position, extend the medicine ball in front of you. Then, bring the ball back toward your chest and lower your upper body down to the starting position.

Muscles worked: abdominals, pectorals, triceps, shoulders

180-degree squat

Begin in a standing position, holding the medicine ball at chest level. Squat down, drawing your buttocks as low as possible while keeping your heels on the ground. Then, in a very fast and powerful motion, drive your body back up, jumping as high as possible while simultaneously turning 180 degrees in midair. When you land, you will be facing the opposite direction. Now, take a deep breath and prepare to go into your next repetition, holding the medicine ball at your chest the entire time.

Muscles worked: quadriceps, glutes

Toss squat

Hold the medicine ball at chest level while standing, then slowly squat down, trying to drop your buttocks as low as possible while keeping your heels on the ground. Then, while standing back up, extend your arms overhead as if you are doing a shoulder press. But instead, toss the medicine ball up in the air. When you catch the ball, in one seamless movement, immediately return into a squat position. This is another fast-paced, rapid-fire exercise.

Muscles worked: glutes, shoulders, triceps

Alternate-arm pushup

Begin in a pushup position, keeping your knees on the ground if necessary. Place your hands shoulder-width apart, with your left palm on the ground and your right palm on the medicine ball. Your hands are now in a staggered position, and you have to steady your body. Then, perform a pushup. When you come back up and fully extend your elbows, you will then bring your left hand onto the medicine ball and move your right hand onto the ground, arms extended at this time. Perform another pushup, alternate arms and repeat.

Muscles worked: pectorals, shoulders, triceps, abdominals