My lower back is pretty safe. Only occasionally does it get angry, but no load is required. Just a simple bend over to pick up a rag,
I needed to work on the floor jack. I can't lift the thirty or so pounds without risking, not just pain, but further and permanent damage to the shoulders. I have a folding table, I stand one end up, and tie a pulley up on that end, a pulley on the jack, tie to the jack, up to th top pulley, down to the pulley on the jack, and hoist away. The load is on three lines, up a ramp,, no more than ten or twelve pounds.. tie it off on the high end, carefully lift the other end and set the legs.
A five second job turned into about fifteen minutes, but I don't get hurt.

When I was 21, had a 24" waist, bought my clothes in the boys department,, Man, that made me mad,  I could clean and jerk 150pounds and get it to full extension and back to the floor in the house without smacking the floor. I don't think I weighed 120,

It's a hard adjustment to have to make. I have a friend, bad knees, screws in his back , overweight and he is finally starting to listen to me. I have to slow him down all the time. He bends over to pick up a scrap of junk in the shop, because I'm working on his car and he thinks he owes it to me. Heck, it'll sweep up.. leave it..  I've learned, some directions, not even five pounds, or the shoulder might pop and I scream like a little girl. Guys, once they're screwed, even surgery isn't a sure fire fix. And the physical therapist who visited twice a week told me that is THE hardest, most painful surgery to recuperate from.
Be careful with it.