Joshua lost his heavyweight belts to the undefeated southpaw in September, outpointed by Usyk in Tottenham Hotspur Stadium.
The Briton has activated a rematch clause to face the former cruiserweight champion again, with the second bout expected to take place next spring, and he told BBC Sport he is still “angry” about his most recent loss.
“I know I can be better than that night,” said Joshua, 32.
“It’s easier to say than it is to do, but within my heart and soul, my brain and body, I truly feel I’ve got a lot more to give.
“I’m angry. It’s growing, but it’s fuelling me every day.
“I think people still recognise me as champion, even though I haven’t got the belts round my waist. They know I’ve got the capability of becoming champion.”
Joshua recently visited the United States in pursuit of a new coach to alter his gameplan for the rematch with Usyk, who outboxed ‘AJ’ for the best part of 12 rounds and almost stopped the Briton in the final seconds of the final frame.
“I had to make changes,” Joshua said. “If you remain the same, you get the same results.
“I’ve got to look at myself, I can only be accountable for me. I’m angry at myself and the only way I can be in a better place is to get myself right by going out there and performing.
“It’s going to be like this for a few months. I do things with a smile on my face, but behind that there’s a lot of tension brewing, and the only way to get it out is by training and performing.”
Joshua was on course for an all-British heavyweight unification bout with WBC title-holder Tyson Fury, but the chances of that long-awaited fight coming together took a hit when AJ lost to Usyk.
“When that fight happens, it happens,” Joshua said. “There’s been one hurdle then another. I can’t keep chasing what’s not in front of me.
“What’s in front of me is to become three-time heavyweight champion of the world, and that’s the motivation.”
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