However, if your only goal is to remove (or prevent) back pain, there is an even simpler recipe: walking.
Your body is built to walk. Literally. You are a walking machine. Walking will put your body back into order. Posture, circulation, digestion, metabolism (modestly) ... every function of your body was built to respond to the activity you are built to do: walk.
Nothing to learn, no fees to pay, no equipment to buy. Just walk. Bonus: it's mentally stimulating, interesting, and relaxing. Your mind will respond to it just like your spinal column does.