How do exercises for low back pain help?

There are lots of reasons why exercises for low back pain are helpful:

They Improve your flexibility and strength
They increase your endurance and stamina
They give relief from some of the postural stresses and strains that your body is subjected to ie sitting for long periods
They improve your blood supply and the general fitness of all the tissues in your body.
They are helpful because they encourage the release of endorphins, these are the bodies own natural pain killers and can improve your mood and reduce your pain.
Exercise puts you back in charge of the problem. This is a really important effect, you are put in control of your back pain, not your back pain in control of you.
One of the biggest problems I deal with in my practice is fear avoidance behaviours. A graded exercise programme can help overcome this problem.