Don't let the TV ads convince you to buy some bulky contraption that will gather dust in your closet, crunches are safe and effective! This video clip shows how to do crunches with varying degrees of difficulty based on your ability. Remember that ab exercises alone will not give you abs! If you have the best abs in the world they will be completely invisible if you are overweight. Aerobic exercise and proper diet are even more important than ab exercises in getting that sought after 6-pack.