Lying on your front, head turned to one side, hands by your sides. (If necessary, you may put a pillow under your chest, but not under your waist, in order to get comfortable.)

Raise one leg off the ground, keeping your knee straight, making sure your thigh comes off the ground. Repeat 5 times each leg.
Raise your head and shoulders off the ground as high as you can. Repeat 10 times.