From his ironically titled book "Got Fight?".
"... you don't want to be that guy who quits in the ring - that's unforgiveable. If you quit because you don't want to get hit anymore, you took the hairy vagina way out. If you want to be a man, take the hits and get knocked the fuck out. My philosophy on getting knocked out is that it renders you unconscious and numb, so why worry about it."