I heard about the Alexander Technique several years ago. To really do it right, you have to go to an Alexander trained teacher, who will work with you one on one to teach you how to move your body correctly. The little bit that I know about it and have applied has helped me, though I usually don't remember to apply it. This will be a brief introduction, with links to sites that will tell you more.
The Alexander Technique was devised by an Australian actor named F. M. Alexander in the late 19th century. He kept losing his voice on stage, and discovered it was because of his posture. Many actors, musicians singers and sports players have been through the training over the years. It helps them to use their bodies more efficiently, and to perform better.
If you watch how children move, you will see that their heads are directly above their necks, not thrust forward, as many adults are; they crouch by bending their knees and hips, not their waists, as adults tend to do. Their movements are fluid and natural, with muscles and joints loose and relaxed. As we grow up, we tend to hunch over our book or our computer, muscles tensed, then wonder why we hurt. The way we move is automatic, habits.developed over the years. This video illustrates how our bodies move, versus how they should move.
The Alexander Technique reteaches the body to move as we did as children. I takes practice, and I can see the benefits of having a trained teacher to work with. The basic concept is to release the tension in your muscles, and allow them to lengthen. The alignment of the head, neck and back is key. Imagine how women align their bodies in order to carry large loads on their heads. If they had their heads forward, as many Americans tend to do, their necks would hurt in almost immediately..
Stand up as you normally do. When someone tells you to stand up straight, the tendency is to push the chest forward, and the head back. That can be just as tiring as the normal slouched posture. Instead, try this: 'Let the neck be free;' 'Let the head go forwards and up'; 'Allow the back to lengthen and widen.' Alexander called these his 'conscious projections', and had his students memorize and practice these words until they were automatic.
The head, neck and back alignment is the main thing that I have learned and applied. I have had months of intense pain around my right scapula (shoulder blade). One thing that helped, and I think ultimately got rid of this pain was readjusting my posture. While sitting or standing, I would take a good breath in, and relax my muscles as I breathed out. I would imagine a string from the back/top of my head gently pulling upward, straightening and lengthening my spine. Breathing in again, I would envision the air spreading throughout my neck and upper back, leaving everything loose and relaxed. Here is a good explanation of how the Alexander Technique can help with chronic pain.
The Alexander Technique has very specific instructions for standing, sitting, laying down, getting up, and almost any activity you might want to do. The ideal would be to have a trained instructor teach you, but that can be expensive. Here are some books and a DVD that can help you learn on your own.