I think a clear distinction needs to be made between something which is 'all in your head' and something which is driven by your internal psychological state(wh

I think a clear distinction needs to be made between something which is 'all in your head' and something which is driven by your internal psychological state(which, surely, can be influenced by other physical sources, but I digress). In my experience with back pain(which varies a bit, due to several types of back pain), I believe most of my issues stemmed from my psychological state and were not "in my head". First off the back is poorly evolved for modern, upright, bipedal life, so it's not surprising that it would be a common source of issues for modern man. That said, there are still patterns and behaviors one can learn, and which do not necessarily develop automatically during childhood, which can allow the back to function without so many issues(See Stuart McGill and others. i.e. hinge at the ball joints, limit loaded spinal flexing, etc). Further, there are psychological states, stress, sadness, depression, which can affect posture, specifically thoracic posture, which contribute dramatically to back pain. Since learning better movement patterns and becoming aware of my psychological connection to my posture, I have, at 46 and after years of pain, been able to vastly reduce my chronic back pain. Another big piece of this was improving my proprioceptive senses as well. When I did manage to improve my posture, it felt quite wrong, both because of the proprioceptive sensations as well as how it felt out of alignment with my moods(i.e. it's odd to puff out your chest when you're depressed). "Modern posture", with excessive thoracic curvature, rounded shoulders, and overall "turtle"/"protective"/"insecure" (all my terms for myself) posture is a major component of spinal pain, even into the lumbar region. Obviously back pain is complex and many folks have other issues than I have experienced, but I think it's worth mentioning that sometimes the mind is the issue but that the issue is not in the mind.