Great Britain's former WBA heavyweight champion David Haye has announced his retirement from boxing.
Haye, who turned 31 on Thursday, always said he would not fight on past the age of 30.
"It has been my intention to retire from boxing on this day ever since I first laced up my gloves as a skinny 10-year-old," Haye said in a statement.
Haye's last fight was against Wladimir Klitschko on 2 July, when he lost his WBA title in Hamburg.
There had been speculation Haye could fight Wladimir's older brother Vitali in 2012, despite reports earlier this week that the Londoner did not want to renew his boxing licence, which runs out in December.
"I know that Wladimir won't fight me again," Haye told BBC Sport. "Vitali is a different case, he is someone who would give me the opportunity to give me my credibility back.
"But that fight is not going to happen so you have to move on."
On Tuesday, Vitali's promoter Bernd Boente told BBC Radio 5 live that he has been in talks with Haye's trainer, Adam Booth, about a possible bout next year.
But Haye denied that the announcement he is quitting the sport was a tactic in negotiations to try to secure that fight.
"If this was something I'd just come up with last week I could understand people saying that," Haye explained. "But I've been saying since I was an amateur that I would retire on my 31st birthday, so this is the day.
"I love boxing, I love training, but you've got to call it a day sooner or later. Too many fighters over the years have gone on way too long. Now's a great time. I feel healthy, there's no damage, why not?
"Vitali Klitschko did show an interest in sharing a ring with me in 2012. But since that initial declaration we have heard the wrong noises from Team Klitschko, which has left me thinking there is little chance of the fight ever coming to fruition."
When asked whether he would consider another big-money fight, Haye added: "I doubt it."
And he says he already has plans for life outside the ring.
"The next phase of my career will be acting," said Haye. "I'm going to study acting and be the best actor I can be.
"I'm going to take the same mindset I had in my athletic career because to get anything out of life you have to put in the hard work and graft. I'm looking forward to challenging myself."
Despite finishing his career with a poor performance, his trainer Booth said it was up to the public to decide where he ranked among heavyweights.
"People will remember David as how they choose too. I have fond memories of the ups and downs," he told Sky Sports News.
Haye, who had moved up from cruiserweight to take the heavyweight title, lost it in a unification bout when he was beaten convincingly on points by Wladimir.
The Briton claimed afterwards that his performance against the WBO, IBF and IBO champion had been hampered by a broken toe.
Haye had previously won the WBA belt by beating giant Russian Nikolay Valuev on points in Germany in November 2009.
He then defended his title by stopping American John Ruiz at the MEN Arena the following April.
His other successful defence came against compatriot Audley Harrison in Manchester, when he produced a devastating display to force a third-round stoppage.