Damned back problems, eh? So common and yeah... all it takes is once and it'll nag you forever. I've got other contributing issues but I remember my first time as well (you always remember your first time). I was a young and mighty Beep, all of 20yo... maybe 21, raging away at the world, strong as a donkey and smart as a tire iron. I was boxjitsuing my way through a small warehouse of stuff that needed to be sorted and had to drag a small but deceptively heavy crate of junk out from a bottom shelf. I lunged at it, twisted to pull it out and "KAZZZORPPPP!!!"... lightning shot up my lower back. It was just a little tender for a few days but that was the first zap out of hundreds... perhaps thousands up until present day.
If I knew then what I knew now I most definitely would not be in the crummy position I am today... but yanno, young, stupid, invincible. You know the schtick.
Anyone needing tips on avoiding/alleviating back pain let me know. I'm a freaking master at this point.