I recently posted about Esther Gokhale's excellent book - 8 Steps to a pain free back.
One of the commenters pointed to a similar book - Ageless Spine - by Kathleen Porter. This is another excellent book, which has a very similar argument to that of Esther's book. The idea is to regain a natural posture, with your spine properly supporting your body. In some ways it is a little more easy to read and understand but both books are excellent.
Here is a video of Kathleen explaining more:
and......here is this knowledge in practice (thanks Davie)