Stand in the shallow end of a swimming pool. The water should come only to your chest. If you are uncomfortable or unfamiliar with your face under water, wear a swim mask and adjust it snugly to keep water out of your eyes.
Inhale and fill your lungs with as much air as you can. Hold your breath.
Bend at the waist in a slow, deliberate motion until your face is in the water. At the same time, place your hands on the front of your thighs. Do not put your entire head under water, only your face.
Slide your hands down your thighs toward your ankles until your feet come off the bottom of the pool. You will begin to float with your back horizontal with the water's surface.
Extend your legs behind you. Extend your arms in front of you until you are completely prone in the water. Keep holding your breath.
Draw your knees into your chest while pulling your arms toward your body to end the prone float. Stand up again on the pool bottom in a deliberate motion. Let the air out of your lungs when your face comes out of the water.