Lie face up, with your back flat on an exercise mat and your legs extended out in front of you about hip width apart and your arms extended behind your head. This is your start position. Proceed to lift your torso from the floor, keeping your arms extended overhead. Until you're in a seated position with your torso and arms at a 90 degree angle to your legs. Hold for a moment at this top position. Lower back down with control to the start position. Repeat for the required number of reps (or time).