Supposedly from earlier in his career during a pre-fight interview.
Thanks
“I’m always going to come in (to the fight) overconfident and I have a reason to. I always come in overconfident because I train so hard that I leave no room for doubt in my mind. I never go in there to lose. The word is not even in my dictionary. I train confident, and I train to think overconfidently. If I didn’t, I’d be a fool.”