While 2) is true - we're talking in comparison to other d1 wrestlers.
And for that group? it's 100% mental. Fear plays such a huge factor. Fear of being tired, fear of giving up points, fear of ending up in bad position - MM just truly doesn't care about it and is willing to exhaust himself and wrestle through that pain.
My post to vhsalum about the kitty was obviously tongue in cheek, but my point is that even mental discipline has its limits. However, that being said, I've read stories about people doing superhuman feats when they are in a heightened mental state. Some time ago, I read about a frantic parent DEADLIFTING an automobile off of their son after a jack had collapsed. (Try that, AJ)
On that note, here is a story about something that I witnessed personally that almost sounds like fantasy fiction from the martial arts movies. When I was young, I used to spend part of my summers at Camp Conrad Weiser which is a YMCA camp outside of Reading, PA. I'm betting some of the other guys posting here went there too. It was a great experience. Most of the camp counselors were college students that took the position for both the experience and as a summer job. In summer of 1964, one of the camp counselors was a student from Albright College named Hidy Ochiai. Any of you guys who are really into Japanese karate would recognize his name because he is quite well known on the East coast. Hidy was not a big guy - he was about the same size as Beau Bartlett.
One of the "activities" at the camp was working on improvement projects. One day, a couple of campers and a counselor were clearing out a path, and there was a huge buried boulder obstructing the way. The counselor and 3 guys were straining on a 6' digging bar to pry the boulder out of the ground, but it wouldn't budge. Hidy happened to come by and saw what everyone was trying to do and said, "Let me try." He squatted down and grabbed the boulder by one end and made this intense look like you would expect from someone like Bruce Lee. Then he exploded and ripped a huge rock out of the ground that four guys couldn't budge with a pry bar. After it came loose, he just rolled it off to the side and then dusted off his hands and smiled at everyone else who was standing there looking at him incredulously. I have no idea how he did that, but it sure makes me question where our physical limitations really end.