Start by lying on your back. Lift your legs into a "tabletop" position: with your knees directly above your hips and feet directly out from your knees, bent in a 90-degree angle with your shins parallel to the floor.
Interlace your fingers and place your hands behind your head, with your elbows pointed out to the sides.
Inhale to prepare, and as you exhale, peel the back of your head, the back of your neck, and finally the backs of your shoulders blades off the floor. Keep a ping pong ball-sized distance between your chin and chest and keep your elbows wide. Inhale to lower back down with control.
Repeat 20 times.
"Keep your legs still the whole time. This will wake up your deep abdominal muscles, your transverse abdominis, as well as your rectus abdominis — the long six-pack muscle," Jetter says.