Having worked with clients with back, knee, ankle, foot, shoulder, neck, and generalized pain, I can attest to the power of the mind in the treatment of pain--above and beyond physical treatment modalities.
This body-mind connection is the rationale behind my work with clients, which always includes a wellness coaching component. I realized that, while I could train back-pain clients to do back- and core-strength exercises very effectively and relieve their pain within minutes of working with them, a handful of my students had their pain return (or move around) despite continuing their prescribed exercises with perfect execution. I learned very quickly that the mind can have unbounded control over the body's experience of pain. So much so that people with back pain undergo surgery, injections, manipulations, and astronomical medical bills trying to alleviate their pain, and nothing works. The simple reason is that for some chronic pain sufferers, the physical body is not the source of the lingering pain.
Drs. Hadler and Sarno have written and presented brilliantly on the power of the mind to create and alleviate back pain. I highly recommend all of their books, most recently Dr. Nortin Hadler's Stabbed in the Back and Dr. John Sarno's The Divided Mind.
(If you're in the U.S., I recommend using the Indie Store's bookstore finder to locate a local bookstore from which to buy these books, rather than ordering from a big-name store. Here's the link.
Listen to Dr. Hadler's brilliant interview.