There was an old magazine article I remember reading way back when that described (in his own words, apparently) Monzon's training regimen, albeit in very general terms. It said he ran for time rather than distance, and he ran for 45 minutes. In his own words, it was "I don't know how far that is, but it is pretty far."
In reality, it's about five miles at an easy pace, but whatever.
He also admonished those who spar very hard in the gym, saying that was "stupid." In sparring, Monzon always went easy, explaining that the point of sparring isn't to prove oneself to the bystanders in the gym, it's to work on various aspects of your form or fight plan. Sage advice there, I'd say.