I wish I could remember the title and author, but this reminds me of an (unrelated) book on pain management, where the author's thesis is that most musculoskeletal pain is psychosomatic: you can essentially will yourself out of chronic pain once you accept this statement as fact. Does anyone recall the book I'm talking about?
John Sarno perhaps? I found his method very effective. https://www.youtube.com/watch?v=6JVDj2rEOas
I had no idea there was a documentary film about him. Thanks very much for sharing that.