Straight sit-ups with bench
Lie on the floor on your back with both calves resting on a bench or on the seat of a chair; this presses your lower back into the floor, keeping it anchored in perfect position. Place your hands behind your head, fingertips touching and elbows pointed outward. Leading with your chin (don’t crunch up into a ball), use your stomach muscles to sit up several inches off the ground; don’t pull with your arms as you execute the sit-up. Do 3 sets of 25 to 30.
With your legs still on the chair, place your right hand behind your head with your elbow pointing outward. Keep your stomach muscles tight, and use them to pull yourself toward the opposite leg. Repeat on the other side. This works the outsides of the abs and helps to isolate each side. Do 3 sets of 25 to 30 on each side.
With your legs still on the chair, bring your arms straight up over your head with your elbows next to your ears, and stretch. Keeping your arms outstretched and your stomach muscles tight, lead with your chin, and use your stomach muscles to pull yourself up toward the ceiling. Do 3 sets of 25 to 30.
Swing around so the chair is a few inches behind your head. Lying on your back with your legs bent and your feet flat on the floor, hold onto the legs of the chair. Keeping your belly button pressed toward the floor, use your stomach muscles to bring your knees up and over your torso. Return to the starting position. Use slow, controlled motions so that you’re not relying on momentum to do the work. Do 3 sets of 25 to 30.