Premise: Tim Witherspoon (born December 27, 1957) is an American former professional boxer who competed from 1979 to 2003. He is a two-time world heavyweight champion, having held the WBC title in 1984, and the WBA title in 1986. Upon winning his second world title, Witherspoon joined Floyd Patterson and Muhammad Ali as the only boxers to win multiple world heavyweight championships.
Hypothesis: Witherspoon boxed professionally for over 12 years.