Another vote for exercise. It’s good for you in a lot of ways.
I used to have a lot of lower back trouble until I went back to a regular exercise routine. Now I (try to) go to the gym 3 times a week. I do 30 minutes of cardio (stationary bike) and 10 - 15 min. of various upper body exercises, including back extenstions and crunches on the Nautilus-type machines. My back thanks me for it, and so do my heart and lungs. (And my blood sugar.)
Work into it gradually, and consult your doctor if you have any concerns.