How can I stop or lessen chronic back pain without pills?

Find out the cause. The best answer is to determine the exact cause of the pain and have it treated. To do this, you have to go to an experienced pain specialist. If this is not possible, try doing yoga or pilates combined with gentle aerobic exercise.
Exercise. There are many studies on the subject of lower back pain. The majority suggest the best method of controlling chronic lower back pain is exercise to create core strength and loose weight. I also suggest daily stretching and core strength exercises. You can find these exercises at: http://harvardneurosurgeon.Com/pt2.Html.