It is important to check with your doctor before doing this or any exercise if you have any health concerns.

These exercises are intended to be performed slowly with caution paying attention to how your body reacts to each position, stopping the movement if you feel any pain. Instead of pushing yourself to do the movement VISUALIZE yourself doing the exercise until you are able to do the exercise.

You will eventually be able to do the exercise. I know this works because I needed to use this approach to learning many of the positions.