Some of his antics during the campaign had me questioning it, but then he would always bounce back with a massive offensive blitz. It wasn't really until the home stretch when he was working triple shifts that I said, "he wants this bigtime". Also, some on other forums told me I didn't know Trump well if I thought he would want to lose. Fair enough, I suppose they were right.
Ultimately he may have been really surprised, and the gravity of the situation would hit him as much as anyone, but when he is on his A game he's as tough as nails and probably really really enjoys the job. He likes to win, hates losing, and the media being such sob's to him must bother him to no end, as it would any of us.