How can I train myself to sleep on my back?

Well through out the night I switch positions, but I always wake up on my back.I am a rough sleeper, but only sometimes. I would recommend wrapping yourself tightly in a blanket while you are on your back that way you would be less likely to move. Or you could surround the side of your body with pillows so that you are less likely to roll. Or you could get a special pillow that could not apply pressure to the face but sort of be like a foam that shapes to the form of your head.