In a group hypnotic regression that lasted less than 15 minutes, I decided to focus on my back pain which was in part because I was sitting in a very uncomfortable chair. I saw myself as a man wearing a white loin cloth in a simple dirt floor hut. I had long muscles on my arms and legs, and very little hair. I was sitting straight up with my legs before me. I knew I had a wife who was doing laundry down by the river. I worked on a river barge using a long pole to move it slowly from place to place. As the hypnotherapist asked what year it was, what my name was, and where I was, I got that information. I quickly forgot the answers to one and two but three was Assyria.
This was and is a good enough reason for back pain as any.