A few years back I worked for a supermarket. I was moving stock around, when I noticed one trolley just dumped in the middle of storage. Fucker was the drinks trolley too, so all 2lt bottles, added up to about 200-250kg (about 500-600lbs if you're US). Tried moving it, wouldn't budge, so really put my back into it...went round the other side, no budging, so again, really threw myself into it - I'm a big guy, worked bars and pubs for a lot of years so moving stock wasn't an issue..all of a sudden I feel this twinge in my back, really painful, so I stopped..and moved to other side, tried again ha. Pain was too bad so I stopped, went back to normal work.
Fast forward next day, back is killing me I just assume I twinged a muscle, done it before no biggie, I keep working..for like a week. But pain get's worse and worse, so I take some time off. Go back in after a month as it stopped hurting, first twisting motion the pain comes back. Rest, go back, repeat..go home.
After about 6 months they send me to hospital, Xrays shows something weird, so then I have an MRI and sent to a back specialist. Turns out I had actually broken my spine, but because I kept working it fused/healed incorrectly, meaning a disc near the break could prolapse under any sort of strain.
Now I can walk about 30mins pain free, lift a few things, but it doesn't take much to screw it.
I'm supposed to have an operation where they open it up and break the spine to let it heal properly...or have the disc removed and the spine fused, both of which ruin my shit for a long time.

My fiance died last year in an accident, so I've just kinda..put it off. It's been hard to give a shit about anything, and having this injury makes it more acceptable to just wallow.