Joshua dropped his heavyweight belts to Usyk in September, losing to the undefeated Ukrainian via unanimous decision at Tottenham Hotspur Stadium.
The Briton has invoked his rematch clause to fight Usyk again, with that bout expected to take place in the first half of next year, and Bruno – who held the WBC heavyweight title from 1995 until 1996 – has offered to help Joshua train.
“This isn’t the end of the ‘AJ’ story. Sometimes in life you have to lose to win – I know that better than most,” Bruno told The Sun.
“Anthony now needs to keep a level head, work hard and come back.
“I think he’s still got the fire in his belly and he’ll want to prove a few people wrong by coming back stronger.
“If I can help in any way I’d love to. He just needs to call me.
“AJ will also want to fight Tyson and prove he’s the best fighter in the world — but that part won’t be easy!”