Now aiming to win part of the heavyweight title a record fifth time, the 46-year-old fighter said he has no patience for those who think he's too old or fear he's putting his health at risk.
"They've been calling me old since I was 30 years old," Holyfield said. "When you come up poor, everyone is always doubting you. Someone always tells you that you can't do something. I never listened then, so why in the world would I get into that thinking now?"
In an interview with the AP Monday, the fighter from the Atlanta area acknowledged that he had little time left in a three-decade career that saw him rise from undefeated cruiserweight to conqueror of heavyweight champions including Riddick Bowe, George Foreman and Mike Tyson.
But he still wants to end his career on top, and to do that says he has to reunite the division's top belts as its undisputed champion. The improbable comeback quest begins Saturday night in Zurich against Nikolay Valuev, the 7-foot, 300-pound Russian who holds the WBA belt.
"This is not to prove anything to anyone," said Holyfield, who rejected that his latest comeback is linked in any way to recent financial troubles. "I box because I'm skillful and I'm good, and I love what I do."
Holyfield hasn't fought since losing a one-sided decision to then-WBO champion Sultan Ibragimov more than a year ago. He is winless in his past four title fights since beating John Ruiz for the vacant WBA belt in October 2000.
Holyfield, who had his license to box in New York state revoked three years ago, underwent five hours of tests in Germany last month to show he was fit to fight. He is expected to earn between $750,000 and $1 million for fighting Valuev, with bigger purses in potential unification bouts.