Calisthenics are exercises designed to build strength by using your bodyweight against the resistance of gravity. Calisthenics require only a small amount of space and do not require equipment. The exercises involve lifting, pushing and pulling your bodyweight by simultaneously engaging multiple muscle groups. Combine a variety of calisthenics to achieve a challenging total-body workout. The simplicity of calisthenics eliminates possible excuses for not exercising, such as lack of time or money, because all you need is your body. Perform calisthenic workouts two to four times per week on nonconsecutive days. Complete one to four sets of 10 to 25 repetitions of each exercise, depending on your strength and endurance.

Pushups are effective for strengthening your chest, arms, shoulders and abdominals. Because they can be modified to accommodate all fitness levels, pushups are versatile as well as effective. Begin your pushup by placing your hands on the floor, directly underneath your shoulders and straighten both legs so that you are balanced on the balls of your feet in a plank position. Bend both arms at your elbows and lower your body 3 inches off the floor. Straighten your arms to return to your starting position. For advanced pushup variations, open your legs slightly wider than hip-width distance and perform with one arm at a time. For a less-intense modification, rest your knees on the floor and form a straight line from your shoulders to your knees.

Handstand pushups target your shoulders, biceps and core stability. Use a wall or spotter for balance. Bring one foot forward, bending your knee as you lower your hands to the floor while simultaneously kicking your back leg up until you are inverted in a handstand. Bend both elbows, lowering your head toward the floor. Straighten your arms and return to your starting position. Handstand pushups are an advanced movement and should not be performed by novice exercisers.

Triceps dips require the use of a bench, step or chair to provide elevation. Sit with your hands on the edge and your knuckles facing out. Straighten your arms to lift your bottom off the surface and extend your legs so that your rear body is 2 to 3 inches away from the surface. Bend your elbows back, keeping them close to your body as you lower down below the surface. Straighten your arms to return to the starting position. Modify the exercise by bending your knees for a lower-intensity variation.

Squats are effective for strengthening your gluteals, quadriceps and hamstrings. Squats are versatile and, when modified, provide variations to meet all fitness levels. Begin a basic squat by standing with your feet hip-width distance apart. Bend your knees as you lower down until the back of your thighs are parallel to the floor. Keep your knees behind the center of your foot and straighten your legs to return to your starting position. Modify your squats to a wider starting stance to target your inner thighs. For advanced variations, jump up at the bottom portion of your squat to return to your starting position.

Leg lifts strengthen your rectus and transversus abdominis. Begin lying on your back, maintaining a neutral spine and activating your transversus by drawing your bellybutton toward your spine. Keep your arms on the floor by your sides as you extend both legs toward the ceiling. Keeping both legs together, extend at your hip flexors and lower your legs to a 45-degree angle. Use your abdominal strength to lift your legs back to your starting position. For a less-intense modification, keep both knees slightly bent and decrease the angle at which you lower your legs. For an advanced variation, keep your head, neck and shoulders lifted while completing your leg lifts.