“I just don't have the desire no more, I don't have the stomach to do it no more. I don't even kill insects in my house. I just don't kill anything no more. I used to kill pigeons, rip their heads off, 'You dirty rat pigeon!' I don't even have the heart to kill an animal no more. I just changed my whole life in general. That probably could have changed the way I fight.”

Debating Linus Pauling, in The Nuclear Bomb Tests...Is Fallout Overrated? : Fallout and Disarmament KQED-TV, San Francisco (20 February 1958) http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/peace/papers/1958p2.1.html
Context: I don't want to kill anybody. I am passionately opposed to killing, but I'm even more passionately fond of freedom. The freedom of Dr. Pauling and of myself expressing our opinions freely on any subject, however broad, however far removed of our proper competence, but particularly, to be able to express our opinions in the fields we really know; this would not be possible in Russia.

Jackass: The Movie

1910s, Address at Milwaukee, Wisconsin (1912)

http://www.usatoday.com/sports/columnist/saraceno/2005-06-12-saraceno-tyson_x.htm
On boxing

http://sports.espn.go.com/espn/print?id=2083509&type=story
On boxing

http://www.abc.net.au/news/stories/2005/06/12/1390287.htm
On boxing

[points to head]
NBC interview (1987)

As quoted in an interview in Vanity Fair (August 2000).