Lie face up, with your back flat on an exercise mat. The soles of your feet should be locked together with your each knee touching the floor, creating a diamond shape. Your arms should be extended behind your head on the floor. This is your start position. Proceed to lift your torso from the floor, keeping your arms extended overhead and legs still. Reach all the way forwards touching the ground in front of your feet. Immediately reverse the movement and lower back down to the start position. Repeat for the required number of reps (or time).