Anthony Joshua says he is "a different animal, not a sulker" and "will bounce back" from losing his world heavyweight titles to Oleksandr Usyk.
Joshua said he "couldn't see in round nine" after an eye injury sustained in Saturday's 12-round fight with the Ukrainian at Tottenham Hotspur Stadium.
His promoter Eddie Hearn suggested his fighter may have suffered a broken eye socket.
"I can't go back and sulk - that's wasting time," Joshua, 31, said.
Asked after the fight about what went wrong, the defeated Briton said: "I couldn't see in the ninth round, couldn't see anything really because my eye was shut.
"It was a good experience because in adversity you've just got to learn to control yourself, stay on top of things, so when I couldn't see anything - it's the first time that it's happened in a fight."
Hearn had said Joshua had given Usyk, 34, too much respect and would have to make "fundamental changes" to regain the WBA, WBO and IBF titles he lost in the fight.
The Briton has a rematch clause in his contract with Usyk, and later confirmed he would take it.
"This experience today is invaluable. This will have a massive benefit in the next fight," said Joshua, pictured with his swollen eye mid-fightJoshua added: "When I was walking back through the tunnel, I just said to myself, 'I'm ready to get back to the gym, I'm ready to just put that work in'.
"I just want to get back to the gym, get back on the grind and improve, so when I fight these good guys and see that they are hurt I can capitalise on the opportunity.
"It was a great lesson today. I know we can look at it from a negative point of view but, for me, I've got to take it as a great lesson and build on that situation.
"I never tend to look at the opponent. I just tend to look at myself and realise where I went wrong. So it's not so much what he done, it's the opportunities that I gave him. It's not so much him. I'm just going to go back and look at myself and correct my wrongs.
"I'm a different kind of animal. I'm not a sulker. This is a blessed opportunity, to be able to fight for the heavyweight title of the world, fight good fighters time and time again and for people to come out.
"I'm not going to be going home and be crying about it, because this is war. It's a long process. This isn't just one fight and then I'm done.
"I'm going back to look at way that I can improve. Straight away, I've already been watching the fight and thinking 'I could've done that better'."
Fury fight 'doubtful' - Warren
Tyson Fury's co-promoter Frank Warren is now doubtful a long-awaited all-British fight with Joshua will happen after a dominant Usyk became the unified heavyweight champion.
"I don't see it happening now," Warren told BBC Sport.
"If it did happen, what would Tyson have done to him? It wouldn't have gone 12 rounds. Tyson would have destroyed him. Absolutely. The unification fight was there, such a big fight. Heartbreaking.
"What would Tyson Fury had done to Joshua? A better chin, bigger puncher."
Warren said Joshua "didn't have any tactics" and compared Saturday's fight with his June 2019 shock defeat by Andy Ruiz Jr.
"Usyk is a good fighter, he boxed extremely well," Warren said.
"But that was my thing about this fight - Joshua is so vulnerable. He's been like that for ages.
"I thought Joshua would be too big for Usyk, but I knew if he was there at the end, then he's been outboxed. Usyk nearly had him over at the end."
"He was gun shy. Never let his hands go. They can talk all they want about rematches. He's just been totally exposed, like he was against Ruiz. How can he be getting outjabbed by Usyk, who was taking the fight to him? I was shocked at that.
"Even if he was to beat Usyk, what is Tyson Fury going to do to Joshua? You'd have your house on Tyson beating him."
Asked about any future fight with WBC champion Fury, Joshua said: "The road to undisputed is marketing. When I pulled up today, it just reminds me that it's a big circus. This is the greatest show on Earth.
"I'll fight Tyson Fury and Wilder without the belts. The belts are fun, it's great, it's legacy - but with or without the belts, I'll fight whoever. The road to undisputed [champion] is a nice title to have and chase but would you still watch it without the belts?
"The main thing is that you have got two competitive fighters in the ring from UK soil that just want to go toe-to-toe."
Matchroom boss Eddie Hearn admitted he was "gutted" about the defeat.
"He will have to make fundamental changes, he will have to box differently," Hearn told BBC Radio 5 Live after the fight.
"I can't see AJ taking a 10-round fight, he boxes twice a year and maybe that is something we will have to look at.
"He is going to go away and all he will do is think about Oleksandr Usyk. He will be thinking: 'How can I beat him, how can I improve?' He is obsessed with improving.
"I just feel there is so much more Anthony Joshua in that fight but he will have to do a lot more in the rematch to be victorious."
Analysis
BBC Sport's Coral Barry, at Tottenham Hotspur Stadium
Even in defeat, Joshua is a classy fighter.
The word after the fight was that the heavyweight would be heading straight to the hospital to treat a nasty eye injury. But just as he did when he was defeated by Andy Ruiz Jr in New York, Joshua faced the media.
Hours after the 65,000-plus crowd had left the Tottenham Hotspur Stadium, a bruised Joshua sat down and made no excuses for his performance. It's a rare trait in the boxing world to accept defeat by the better fighter.
There were no flashes of anger as Joshua calmly answered questions about what went wrong. There was almost an air of excitement from the two-time world champion at the prospect of overcoming what can only be described as a heavy loss to an exceptional opponent.
Joshua was still confident, and it remains to be seen if that bravado will see him through another dark chapter in his career.
Joshua was able to reinvent himself to beat Ruiz. It will be an even tougher task to do the same to defeat Usyk.
