Anthony Joshua revealed he has developed a new mindset since his last fight in March.
The then WBA and IBF champion also won the WBO title when defeating Joseph Parker and will next fight Russia's Alexander Povetkin at Wembley on September 22. He is ref="https://m.skybet.com/boxing/upcoming-fights/event/22514682?AFF=683&dcmp=sl_bg_betlink_bgnews">1/10 to win with Sky Bet with his opponent 6/1 and the draw 33/1.
A much hoped-for unification fight with WBC champion Deontay Wilder continues to elude him, but despite the expectation they will meet next year, Joshua said: "I used to concentrate on the opponent and always worried what was next.
"I used to box within myself, stopped expressing myself and fulfilling my potential to become a great world champion Not anymore, Jarrell Miller, Wilder, I had issues with Parker. There is always something going on around my fights. Now I'm dead serious about my business, this is chapter two for me.
"Alexander Povetkin is one of the best fighters that I will be facing on my record - and I look forward to it."
The 38-year-old Povetkin, like Joshua an Olympic gold medallist, said: "I want to say that AJ has proved that he's one of the strongest fighters here - and I'm excited about this fight.
"This fight will be all about experience. I know Anthony Joshua is a world champion, but we have been training hard for this fight."