Back issues: Adding new exercises.

fitplease

I have been running c25k for a couple of months now, and am ready to add something else to my exercise regimen. My neuro wants me to swim, but that is not feasible for me at the moment. I used to do 30DS, but that irritated my back and my neuro recommended I stop doing it.

c25k seems to loosen up my hips, so it helps with my back pain. I am thinking about adding a Pilates regimen, but I also wanted to glean some ideas off of fellow MFP'ers to see what exercises you have found helpful. (In particular, ones that strengthen your back muscles.) Please tell me why you chose the exercise(s) you chose, too.

Thank you.