Lie back on a flat bench press with a dumbbell in each hand resting upon your thighs. Ensure that your palms are facing one another. Use your thighs to help you raise each of the dumbbells over your chest (at shoulder width) as you are lying down. Once the dumbbells are positioned over your chest, rotate your wrists forward so that the palms of your hand are facing your feet. This is your starting position. Slowly descend the weights until the dumbbells arrive just to the sides of your chest, pause briefly, and use your chest to push the dumbbells back into the starting position. Pause briefly at the top of the motion with your arms locked and then begin the next repetition.
When you have completed your prescribed number of repetitions, lift your legs from the floor, twist your wrists so that your palms are once again facing one another, and touch the bottom of the dumbbells to your thighs. Then, perform a small kick forward with your legs so that you are sitting up with the dumbbells on your thighs. This will allow you to place the dumbbells back on the floor in a controlled fashion.