Lie on your back with knees bent and feet flat on the floor. Take a deep breath and relax. Press the small of your back against the floor and tighten your stomach and buttock muscles. Do not push with your feet - all the pull should come from your abdominal muscles. This should cause the lower end of the pelvis to rotate forward and flatten your back against the floor. Hold for six seconds; relax for six seconds. Repeat six times.
It may take a little practice to learn this exercise, but it is important and forms the basic starting position for many of the other exercises. While learning, it may be helpful to place a hand in the hollow of your back to feel the small of the back pressing toward the floor. Once learned, the maneuver will become easy with practice.