Brooke Burk with Modern Mom instructs this video on how to do a quick ab work out. Lay down on your back on a yoga mat. Start with 20 basic crunches with your hands behind your head. If you feel it start to hurt your neck, rest your head against your hands. Now do a bicycle motion with your legs, touching your elbow to your opposite knee with each rep. Do 20 reps. Now point your legs into the air and do 20 crunches. Next bring your legs beside you and to the right, and do 20 more crunches. Repeat on the left side. Move back to resting on your back. Let your left leg point straight forward, and bring your right leg up. Hold onto your calf, then switch legs and grab onto the other calf. If you feel a pull in your neck, you can use one hand to rest your head in. Again, do 20 reps. Once you finish these exercises, repeat the whole thing two more times, for a total of 8 minutes.