Get in plank position with the hands and feet as the only points of contact. Tilt the hips into posterior pelvic tilt and maintain a rigid plank for the duration of the exercise.

Slowly descend until the chest is 2-3 inches above the floor.

Press your body up to the starting position. 

DO NOT allow the hips or lower back to dip. DO NOT let go of the rigid plank-- body is a straight line the entire time.