Anthony Joshua is the 6ft 6in poster boy of British sport, perhaps the biggest name in global boxing, a multimillionaire at the age of 28 and the current incumbent of three world heavyweight titles. Despite all that, he says, a 'mid-life crisis' is already upon him.

Joshua defends his WBA, WBO and IBF belts against dangerous and experienced Russian Alexander Povetkin at Wembley Stadium on Saturday night, which will be the Londoner's fourth stadium fight on the trot.

It means that over the course of the last 17 months, well over 300,000 people will have paid their money to buy a ticket to watch Joshua throw punches live in the flesh. It is a four-fight record that no other prizefighter in history has even come close to matching.

But even his current status is not enough to protect him from a pesky existential crisis. Thankfully it has so far manifested only in a reluctance to cut his hair, but Joshua says life as the heavyweight champion of the world is not all it's cracked up to be.

The 20 best Anthony Joshua pictures Show all 21 1 / 21 The 20 best Anthony Joshua pictures The 20 best Anthony Joshua pictures The 20 best Anthony Joshua pictures Anthony Joshua fights Joseph Parker on March 31, so we thought now was a good time to look back at some of the heavyweight champion's greatest pictures. Getty Images The 20 best Anthony Joshua pictures That uppercut Defeating Wladimir Klitschko on April 29 2017. Getty Images The 20 best Anthony Joshua pictures Champion Celebrating after victory over Charles Martin on April 9 2016. Getty Images The 20 best Anthony Joshua pictures Walking tall At the Burj Al Ara in Dubai, in November 2017. Getty Images for AJ Boxing The 20 best Anthony Joshua pictures Unification With Joseph Parker, at the Joshua vs Parker press conference on January 16 2018. Getty Images The 20 best Anthony Joshua pictures The future With Luke Campbell, Tom Stalker, Fred Evans and Andrew Selby of Team GB ahead of the London 2012 Olympic Games on December 2, 2011. Getty Images The 20 best Anthony Joshua pictures Turning up the heat Ahead of the Klitschko fight. Getty Images The 20 best Anthony Joshua pictures Relaxing Taking a bread during a media workout in Sheffield, on April 19 2017. Getty Images The 20 best Anthony Joshua pictures The hype train Talking to the boxing press, on February 19 2016. Getty Images The 20 best Anthony Joshua pictures To the victor, the spoils With Klitschko, after taking his belts. Getty Images The 20 best Anthony Joshua pictures A rare defeat At the BBC's Sports Personality of The Year awards, on December 17 2017. Getty Images The 20 best Anthony Joshua pictures In for the kill Stopping Carlos Takam, on October 28, 2017. Getty Images The 20 best Anthony Joshua pictures The establishment Holding his MBE medal, on February 20, 2013. Getty Images The 20 best Anthony Joshua pictures First belt After defeating Denis Bakhtov to win the WBC International Heavyweight Championship, on October 11, 2014. Getty Images The 20 best Anthony Joshua pictures Dancing Dominic Breazeale stumbles. June 25, 2016. Getty Images The 20 best Anthony Joshua pictures Victory Wladimir Klitschko is beaten. Getty Images The 20 best Anthony Joshua pictures Gold On the podium at the London 2012 Olympics. Getty Images The 20 best Anthony Joshua pictures Getting personal Throwing a punch at Dillian Whyte, on December 12, 2015. Getty Images The 20 best Anthony Joshua pictures Sit down Knocking out Raphael Zumbano Love, on May 9, 2015. Getty Images The 20 best Anthony Joshua pictures Game recognises game Meeting the legendary Michael Watson. November 14, 2013. Getty Images The 20 best Anthony Joshua pictures Fresh faced After victory over Roberto Cammarelle in the Men's Super Heavy (+91kg) Boxing at London 2012. Getty Images

“I've got to the stage right where...what do I live for?” He said, asking nobody in particular.

“What am I doing? Who am I impressing? I am in the gym. You get to a mid-life crisis and you just don't care no more. It is one of those things.

“I was saying to Eddie [Hearn] on the phone the other day, nowadays you see people my age on the beach, driving the most flash cars, living an exotic lifestyle.

“And then you know what it is like when you are younger; I want to be heavyweight champion of the world. You become it and you think it is going to change your whole life, but I've realised it doesn't.

“I am just still sitting here, small room, content with my flat and I just hit a wall where I was like: 'you know what, I just don't care anymore'.

“This is my life, I have got to stick with it and that's probably why I haven't bothered to cut my hair because I have got nothing to cut it for.

“I am not opening Tescos or ASDAs anymore, I have done all that stuff. I am not going to the GQ awards right now. I am just keeping my head down.”

Anthony Joshua is having a mini crisis ( Getty )

With that being said, the fact of the matter is that Joshua's brutal training regime at his usual base of the English Institute of Sport in Sheffield has rendered him simply too busy for a trip to the barber.

Povetkin has been described by promoter Hearn as the toughest opponent of Joshua's career and that includes Ukrainian two-time heavyweight champion Wladimir Klitscho, who was despatched in the centre of the Wembley pitch last year.

That has meant an all-encompassing gym schedule and Joshua says the pursuit of the perfect preparation has even extended to training his eye sockets.

“You have to preserve your body,” he added.

The heavyweight champ wants to protect his body ( Getty )

“We look at stuff like sleeping, the amount of time we spend on our phones, eyes, your eyes have muscles so you have to work your eye sockets, recovery. It is about wellness and how you're feeling.

“I could go in there and knock Povetkin out in a round or two but then there is the eight weeks of intense sparring, doing 200 rounds, you have to protect your body.”

Joshua moved to 21-0 and clinched the WBO title as a result of his victory over fellow champion Joseph Parker beneath the closed roof of Cardiff's Principality Stadium on March 31.

It was, however, the first time in his professional career that he was extended the full 12-round distance and there was some criticism for his inability to put the New Zealander away.

Joshua and Joseph Parker trade punches ( Getty )

Joshua concedes that he feels under added pressure to get back to his destructive ways against Povetkin, 39, but used Lennox Lewis as an example of why he will not necessarily 'go looking' for a knockout.

He said: “When I watch boxing I want to see a knockout so I get where people are coming from because I'm a fan of the sport as well.

“I remember when Lennox used to fight and everyone used to say how boring he was, but now everyone will tell you how great he is and how slick he was.

“It's about winning, beating that opponent in front of you. Every opponent will give you different opportunities and possess different game plans.

“If it is there, believe me I have that instinct to take them out. If it is not there, I know how to box and keep it simple. Sometimes you can go looking for it and you get caught, the tables turn and history rewrites itself.

“I've got to be clever now. These fighters are a bit better than what I used to fight so they don't give me the opportunities that I used to get against lower level fighters.