Wladimir Klitschko says he is glad he lost his world heavyweight titles to Tyson Fury last December.
The Ukrainian, who was champion for nine years, will meet Briton Fury in a rematch in Manchester on 9 July.
"Losing feels good," Klitschko, 40, told BBC Radio 5 live. "I'm glad that my hand was not raised that night.
"Failure is not an option unless it is the only way to get better - and I had to get better. I needed a push to get better and I got it. I feel it."
Klitschko, then the WBA, IBF and WBO champion, lost on a unanimous points decision in Dusseldorf, with Fury's victory considered a huge upset.
"I didn't show my full potential in the fight," Klitschko said. "Physically, I was in one of my best shapes, but mentally I wasn't there, not present in the ring.
"After a while, you get used to defending and not conquering the man in front of you. It will be different on 9 July. t's not a rematch, it's revenge."
'When the chef leaves, the rats dance on the table'
Klitschko, who has suffered four defeats in 68 bouts, had not lost for more than 11 years until he met Fury.
"If you want to destroy a person, give him five years of success. I had no failures for 11 and a half years," said Klitschko.
"After a while it's OK to make a mistake and I made a mistake against Fury. I want to make that clear in my revenge and it is what I'm looking forward to."
Until Klitschko's brother Vitali retired in 2013, the pair held all the major heavyweight titles.
Now Wladimir has been beaten, they are with Fury (WBA and WBO), American Deontay Wilder (WBC) and Britain's Anthony Joshua (IBF).
"Before, it was clear: one champion, one family name," said Klitschko.
"When the chef is not in the kitchen, the belts get lost. When the chef leaves, the rats dance on the table. I want to show who the chef is in the kitchen."
'I didn't think about retiring'
Klitschko denied any suggestion he considered quitting after losing to Fury.
"I got over it," he said. "I was suffering for three days after, then I shook it off.
"Any rumours of retiring were not true. Three days after the fight I called and executed the option of the contract. That was it."
In the build-up to the fight, Fury appeared at a media conference dressed as Batman, but Klitschko said he was not distracted by that.
"In our big boxing family, we have some characters," he said. "I've faced different press conferences with T-shirts and freaks. You don't win at a press conference."
'I'm a fan of Anthony Joshua'
After beating Klitschko, Fury was stripped of the IBF title because he would not fight the mandatory challenger, Vyacheslav Glazkov.
The belt was won by Olympic super-heavyweight champion Joshua this month in only his 16th professional fight.
"There are so many champions but that's no disrespect to Anthony Joshua, because I've always been a fan," said Klitschko.
"He's a talented guy that will conquer the division for a long time.
"He still has a lot to learn, but I'm putting a lot of hope in him. He will represent the heavyweight division better than Tyson Fury."