OK, it happened, I've done my back in.
For a few days I felt more tired in my lower back than usually. The hot tub helped a bit, but not fully. So I tried to be careful. I monitored my working positions and tried not to lift anything heavy in an abrupt manner. One evening I was digging up some daphpodil bulbs and then I was going to store them, but an iron rod was in my way. I "just" wanted to move it a but and that was enough.
Since then I walk like a very much more elderly person...
Well, I know the deal. I try to walk as much as I can, I put on cold and hot packages and I try to exercise patience, which is an extreme challenge for :-)