I pounded sand with pebbles in it way back in the
Post# of 51175
way back in the teenager days.
I got my knuckles cut and bloody.
Smashed them again a few times.
Karate.
I did get a 1st layer of callous.
And then never did it again.
Such is the way of a 1/2 man.
More than 50 years ago;
doing a lot better these days.