I didn't like smacking my two sons when they were little, but whenever I swore in front of a female secretary at my unit, my Squadron Sergeant Major (SSM) would give me 20 push-ups as punishment. I tend to swear a lot, so I got pretty fit.
Hmmnnn, so whenever my two boys (then aged 6 and 7) stuffed up, I'd give them push-ups too. Now being my boys, they're both smart-asses, so they'd try to annoy me by doing a "go-slow" on the push-ups, so I'd say, "Last one does another 10!" and that'd get 'em going.
I figured that, as opposed to smacking them, they were still being punished, but I wasn't hurting them, so I didn't feel bad, and even though it might have hurt them just a little, in the long run, it was good for them. By the time they attended junior high and they were "introduced" to push-ups by their gym teacher they could easily do 50+ push-ups, and excelled at most sports.
Now they're both very fit young men (22 and 23) who've never been in trouble with the law, and have a healthy respect for "doing the right thing". I think I owe my SSM a beer. Cheers, Terry.