Key is doing the sit-ups slowly, back flat on the floor, feet flat on the floor (so your knees are in the air), fingers locked behind you neck, and crunching forward as far as you can, without lifting your back or feet off the floor. No need to do the full blown thrashing forward sit-ups, they really do nothing apart from strain your back. Crunch sit-ups will fully work your abs. It is important to exhale as you crunch forward, and then hold the "crunch" position for a few seconds before relaxing back. Do the same but rotating left and then right for a complete work-out. This method is great for strengthening your abs, without straining your neck or back muscles.