Start with a little warm-up to ensure you don't pull anything. Rotate your head around your neck in a circle clockwise for 20 seconds. Then rotate it counter-clockwise for 20 more seconds. Lower your head slowly so that you are looking at your feet, then raise it up until you are looking at the ceiling. Repeat 10 times.
After you have adequately warmed up, lie on your back on a flat, sturdy bench with only your head hanging over the back edge. Place a towel underneath a 10 pound weight and rest the weight gently on your face, holding it with your hands on either side just enough to keep it balanced. With the weight still resting on your face, slowly lower your head until it is almost perpendicular to the ground, then raise it until your chin touches your chest. Repeat 10 times and do 4 more sets.
Turn over and lay flat on your stomach. Place the weight on top of your head just as you did before with your face. Slowly lower your neck until you can see behind you, then raise it until your head is level with your body and you are looking straight ahead. Repeat 10 times and do 4 more sets.