Back pain and Literature

Okay, so I go to get an injection in my back and the doctor says that I have arthritis in my L4 joint. What exactly does that mean? I say. She says, you have no cartilage left between these two bones. I can't see any. OUCH! So she gives me an injection there to see if that's the spot and now we wait. The funny thing is--people respond to my back pain entry, but not to comments about writing. This is what's happening to us--we're getting older. The problem is, all the doctors kept saying, but you're not old enough to have arthritis. I keep telling them--aerobics! I taught aerobics for twenty years: high-impact, step, low-impact, you name it. I ran for so long, I broke my foot in two places. Now, all I can do is walk. I guess I'm going to have to switch to swimming or yoga.