Evander Holyfield has declared that he is "unretiring" from boxing. The former four-time heavyweight boxing champion has decided, at the age of 50, to come out of retirement again. "I already told people I was going to retire." Holyfield told Sports on Earth. "But this morning, when I woke up, I thought about it some more. Now I'm not going to retire. One can change his mind, can't he?"