Never was in a coal mine. But I've played around quite a bit in a hardrock mine.
Absolute back breaking work. You need to be in prime physical condition.(which I ain't anymore.)
You could get killed quicker than the time it would take you to realize you were dead.
You'll eat like a horse and sleep like a baby. Probably in the bathtub.
But sleepin in the bathtub is a good idea. Take at least a week after you come out to get the grunge out from under your fingernails.
Ain't no worse than lawyerin'.