If your body is saying, "No, please, let me rest," then don't keep hurting it. It needs the rest. It knows best! It's evolved for this. If you were a hunter and you were out on a hunt and your back/leg/knee/muscle suddenly gave out, you'd be so much chow for the big beasty you'd been chasing, instead of the other way around.
Basically, my core muscles are bollocksed, my back muscles are sick of taking the strain, and it's entirely possible that my spine is or isn't crumbling, because nobody's ever actually referred me for a goddamn scan.