I got problems doing sit ups and the strange is, I am only 16. I would consider myself as healthy with no problems, I can do anything without getting any sort of pain. If you see the attach you would see where in the lower back it hurts. And yes, I am doing sit ups correctly and no, I ain't going to try something else. Since I do other exercises where my lower back also hurt. I don't know what the problem is, I got nearly no flesh there, but that is sort of normal I think. Anybody can help me out?