I read a stupid book about self-hypnosis as a kid which described a useful technique called progressive muscle relaxation. While resting, you start at one extreme, like the toes of your right foot, and focus on relaxing (or tense then relax) that part. Then move up to your ankle, then calf, then thigh. Repeat for the other side. Do the same for your arms. In most places nothing special happens, but when you focus on your lower back or especially your upper back and shoulders and neck, you find some tension was there that you didn't realize. It's hard to get out of the habit of holding your big head up all day, I guess. It's weird to feel like you were already relaxing and then find that you can relax more. I have done this in a dentist's chair and found that my whole body was tense and stiff.