Probably the most important thing people can do to help their low backs is to stretch their hamstrings.  Tight hamstrings are like ropes that pull the pelvis backward and "flatten" the lumbar spine.  It is VERY important to stretch the hamstrings by pulling the leg to the body- not reaching toward the toes.  

Lying on you back, and pull the leg to you.  If you trying to stretch your hamstrings by reaching for your toes, you risk further injury to the low back.
Click the link below to learn more about proper stretching...

It pays to stretch yourself in life.
Dr. John's Chiropractic