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  The two heavyweights fight for the IBF title and vacant WBA belt in front of 90,000 fans at Wembley.
  Joshua, 27, says his 13 weeks of preparation have been "tougher times than I have had in any walk of life".
  Klitschko, 41, lost his heavyweight title to Tyson Fury in November 2015 - his first defeat in 11 years.
  In an interview at his Sheffield training camp before the biggest fight of his career, Joshua spoke about his motivation, being a "man of the people", the state of British boxing, and his family.
  Joshua, unbeaten in 18 fights since turning professional in 2013, said he is not worried about his safety in the ring because of the intensity of his training before the fight.
  "I've been pushed to places I've never been pushed before," said the Briton.
  "I think I take more punishment in the gym than I do in the fights. Sometimes I try things and it doesn't work and I've broken my ribs, my hand, dislocated shoulders in the gym but we get it right for the fight.
  "One of the main things is his mindset at the minute. He claims he is obsessed and I ask 'What is he obsessed about?' I look at myself in the mirror and it is about beating me.
  "I've lived simple. I've been training under the dark light so I can shine under the bright lights on April 29."
  Joshua had numerous incidents with the police as a youth, including being arrested for ABH, drug possession and being electronically tagged. He has previously stated that he would have been in jail were it not for boxing.
  But Joshua said: "I've had tougher times in the gym than I have had in any walk of life at the minute.
  "I put myself through it and it is important to because I don't want to be star of the gym and then when I get to the fight it's like: 'I've never faced this type of warrior before.'"
  Asked if this is the defining fight of his career, Joshua replied: "It is one of them. If this was towards the end of my career, I would say: 'This is the defining fight that's going to write the history books.'
  "But I've still got so many more years. I'm confident. I'm learning about myself, so this fight is, for me, one fight that I've got to take in my stride round by round and when I take that attitude the victory comes and we move on and there are so many other big fights in the UK."
  Joshua does not believe Klitschko has underestimated him, saying: "He's coming game, he's coming ready, and the body does what the mind tells it. His mind seems to be in the right place so I'm in for a tough fight."
  "I may not express myself flashing what I've done and telling everyone I'm the greatest," he said.
  "Where we grew up, everyone was about making money, but low key, understated - you probably didn't want to get your house burgled!
  "Who I am when I was 17 is who I am today, so not much has changed.
  "You've got to add a bit of flavour. It's needed now and again, but it's got to be real because I don't take boxing as an act. This is way of expressing myself and being true to myself and there are kids watching so you've got to be mindful.
  "If I was to be that type of person - loud and trashing tables - after a fight, I would still continue to be that way. What I notice about fighters is they act a certain way and once the fight has started they are hugging each other and are quiet.
  "I'm just trying to be myself on camera, in the ring, outside of the ring and off camera."
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  Asked about being very accessible, Joshua says: "It's part of boxing. It is good to lock yourself away but I'm a man of the people, it's no bother. As long as it doesn't make me late for training, I've no problem speaking to 100 people.
  "I'm in the same flat that I've been in since 2011 - it's been a long time. I think I'll be one of those guys who will learn the piano, the violin, bungee jump and do all the things I didn't do when I was fighting.
  "When I'm not fighting, I try to take a holiday and experience things, but when I'm fighting the simple life has worked and I don't try and change it."
  "I was on the complete opposite end of healthy living before boxing, it's got me strong," he said.
  "I'm a superhero to my little cousins. It's what it does for my family and my surname Joshua.
  "People are proud to wear that name and I'm representing my family. It is nice to have kids supporting you. It's reaching out to a wider audience.
  "I'm just a normal person. You have your good days, your bad days, you have road rage, everyone goes through it.
  "You've just got to live by the job you do and if that's what comes with it I'd rather choose winning over anything."
  Joshua, who turned professional after winning gold at London 2012, said: "When I first turned professional, no-one would touch me sponsorship-wise and no-one was really backing boxing.
  "I say look at the characters of the sport, look at the individuals, get behind the gloves."
  He praised fellow Brits Tyson Fury, who won the heavyweight title with a win over Klitschko in November 2015, Dillian Whyte, the WBC International heavyweight title holder, former British and Commonwealth heavyweight title holder David Price and Dereck Chisora, who challenged for the WBC heavyweight title in 2012.
  "As I've been in the game, Fury won, Dillian, myself, Chisora the likes of Price, up-and-coming heavyweights and lighter weights - it's definitely brought more attention."
  Asked if he was worried about his mum watching his fights, Joshua answers: "No, no, no, definitely not. Because she's proud, she's happy and I look after her so I think that's the main thing.
  "I've got a son and I definitely wouldn't want him to fight because of those reasons, his health, it's tough.
  "I did it quietly. When I first started fighting, I didn't tell my family. It was just about me and what I wanted to do.
  "My mum has always seen the positive light of fighting rather than the health issues and I've always been on the road to winning and glory.
  "She's had a few tough times and a few scares when I've lost as an amateur, but we bounce back, and for all the good times she's forgot about the bad times we've had."
target: Anthony Joshua says he will be competing at a "whole new level" when he takes on Wladimir Klitschko in Saturday's world title bout.