I get low back pain, too, Fras. In my case, its from too much sitting at a computer. I know a lot of ppl with back problems find yoga helpful. I don't like yoga too much, but I do feel better when I do regular fitness classes that have an abs & back portion.
Isn't back pain really common as we age? I think our spines & back muscles aren't really evolved (yet) to be really strong in the vertical. As a species, we haven't been walking upright for that long. My point is (there is one) is that the back exercises seem to help. At least me.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh