Sit-Ups Lie on the ground with your knees bent and about shoulder width apart. Keep your arms folded across your chest or place your hands behind your head. If you place your hands behind your head, make sure you are not straining or pulling your neck through the movement. Keeping your feet and butt on the floor, raise your torso off of the ground so that it creates a V shape with your thighs. Return to starting positio.n Continue for 20 seconds. Rest for 10 seconds before starting the circuit over again. Complete the circuit 6 times to finish the workout, with 20 seconds rest between each round.