Anthony Joshua is working on his mental strength ahead of his championship defence against Oleksandr Usyk.
Joshua had been training to fight Tyson Fury in August in order to decide the title of the undisputed heavyweight champion of the world, but the WBC champion has since been sidetracked, and will now face Deontay Wilder in October, assuming there are no further delays.
The WBO then mandated that Joshua had to fulfill his defence against Ukrainian Usyk, and the pair will meet at Tottenham Hotspur Stadium on September 25.
Joshua believes that the southpaw, a former undisputed cruiserweight champion, is his toughest test yet.
He told Sky Sports: "100 per cent, he will be. Movement means you are never stationary to get hit. Movement is important.
"Concentration - when you want to [punch], you lock in, then make a move. You have to make sure your brain works.
"That can be mentally fatiguing so I am sharpening the mind so that I can concentrate for the 12 rounds.
"Also I practice having the ability to [punch] four times, not just once.
"Concentrate, take your time, pin him down.
"It's a fight for the brain. Knowing what you've got in front of you and knowing how to deal with it.
"You can either be aggressive, corner [him], throw everything at it. Or take your time, be clever, then knock [him] out."
With Usyk at the lighter end of the scales for a heavyweight, Joshua is preparing to go the distance with his opponent.
"I do look at my weight but I'm not trying to make weight because I'm a heavyweight," he said.
"I tailor my training. I am getting a lot of experience, I've been fighting good fighters for a long time, I've studied them and learned about their training camps.
"I've learned how to condition my body for specific fights.
"I'm looking trim for this fight.
"I'm fighting a guy who is a 12-round fighter. So it would be silly of me to go in there bulky with my muscles screaming for oxygen.
"I've been training like a 15-round fighter in this camp. I will be well-conditioned to fight. That is key.
"What happens when I train that way? My body adapts and takes its natural form. This is the form it has taken."
After Usyk stepped in as his next opponent, he brought in Thomas Carty and Shokran Parwani as sparring partners.
"I want good sparring, tough sparring because you practice how you perform," Joshua explained.
"We get in some really good sparring partners. You don't want to leave it all in the gym. But as long as you train with purpose, you are going to learn.
"Adversity is when you find out who you are. So I put myself in vulnerable positions and get comfortable.
"Guys with more power than me, quicker than me, a longer reach than me, a quicker jab than me. Through the process, I develop as well.
"It is a process that I am going through, adapting to a southpaw."