As long as it's not structural problems, "low back pain" is relative to the posture of your ENTIRE body, not just your back... You need to think about what you are putting your body through the entire day... What do we do a lot of during the day?...... SITTING... More than likely you sleep on your side w/ your knees slightly bent... Sit at the breakfast table (hopefully), sit in the car, sit in the desk, sit, sit, sit, sit... Probably the worse thing you could do to your body...
With stayin in one position for too long is know as syntergistic dominance... basically muscles get really stronger, while their 'oppositing partner muscle' gets really weak... from there it's strengthening the weak muscles and stretching the strong muscles to fix those imbalances and take pressure of your back/pelvis, etc...