I happened upon this interesting 1977 preview piece on 39 yo, pleasanlty plump, George Chuvalo. I won't give away the result of the fight in question - I'll let you look it up if you don't already know - but if anyone can elaborate on the finer details of the match it would be appreciated.
I'll just say, the opening sequence shows George slowly jogging up a semi-snow covered hill. Part way up, George stumbles but rights himself. However, after reaching the top, he raises his arms in Rocky-life fashion and almost falls over again - that hill almost managed what no other fighter could.
The more I read and see of Chuvalo the more I can appreciate what a man he was/is. Here's the link:-