The IBF world heavyweight champion makes a second title defence against American Eric Molina (25-3, 19 KOs) at the Manchester Arena on Saturday.
But having only begun his bid to dominate the heavyweight division when he turned pro after winning gold at the 2012 Olympics in London, the 27-year-old is already considering the possibility of getting out of the boxing game early.
"Maybe I'll be around for another five years," Joshua said. "The legacy I leave will be I've come up the hard way and I've stayed true to myself. I was a kid from Finchley [in north London] who went to the gym to make something of myself, to get fit. I wasn't chasing money. I was just on a self-development course.
"I can finish in five years provided everything goes to plan. One hundred per cent I could walk away from boxing now, it's all about being happy, and I'm happy. As long I'm happy that is all that matters. I don't do it for the money, I don't do it for the glory nights."