The 15-minute Ab Workout That WORKS

This foodspring video shows you how to do crunches correctly. This exercise targets the vertical abs. Crunches are a great exercise for beginners. Make sure that only your shoulder blades are coming up off the floor. Your lower back should stay on the floor. Your neck should stay in a neutral position.

This foodspring video shows you how to do scissor kicks correctly. This ab exercise is especially good for your lower abs. Lie on your back with your hands next to your sides. Keep your legs straight. Now lift your legs in the air and cross them - left over right, then right over left, like a pair of scissors. Make sure to keep your back flat and not arch it.

This foodspring video shows you how to do foot tap crunches (a.k.a. heel touch crunches, a.k.a. toe tap crunches) correctly. This variation targets the oblique abs. Start in the crunch position, shoulder blades off the floor. Move from one side to the other, using your right hand to touch your right shoe, then your left hand to touch your left shoe. Your upper body should move towards the side along with each arm.

This foodspring video shows you how to do knee planks correctly. Knee planks are a great way to start with the plank for beginners who don't yet have enough core strength for the classic version.Start in the same starting position as a plank, but leave your knees on the floor. Even though you've got your knees supporting you, stick to the same guidelines: Your elbows should be under your shoulders, your abs should be tight, and your glutes should keep tension to support your weight.