To do sit-ups, lie on your back, bend your knees and place your feet flat on the ground. Cross your arms over your chest, and tighten your abdominal muscles to lift your upper body off the floor until your elbows touch your knees. Return to the starting position.Continue Reading
Lie on the floor with your knees bent. Make sure your heels and toes are flat on the floor. Cross your arms over your chest, with your right hand on your left shoulder and your left hand on your right shoulder.
Tighten your abdominal muscles by pulling your belly button in toward your spine. Gently begin lifting your upper body off the floor starting with your head, then your shoulders. Continue lifting your upper body until your elbows touch your knees. Hold this position for at least a second.
Continue to tighten your abdominal muscles, and gradually lower your upper body down to the floor. Don���t lie completely flat on the floor; keep your torso slightly elevated above the floor. Your back should be somewhat arched at this point. Repeat these steps as many times as desired.