Reigning world champion James Magnussen said Wednesday he was working hard on being humble and no longer trying to be the "alpha male" of the Australian swimming team.
The London Games silver medallist, who produced the year's fastest time to win the men's 100-metres freestyle at Australia's world championship trials on Tuesday, has had a torrid time since the Olympics last year.
He was among six Australian swimmers who were fined and handed deferred suspensions last month after admitting taking banned sleeping pills and playing pranks at a pre-London Olympics training camp.
The 22-year-old, whose 47.53sec at the trials eclipsed Russia's Vladimir Morozov (47.93) as the best this year, said he was hugely relieved to have qualified for the Barcelona world championships.
"I have been a bit dodgy with my sleeping because I felt that swim last night was the pinnacle of nine months of build-up," he told reporters.
"I feel really relaxed today having got the monkey off my back."
Nicknamed "The Missile", Magnussen has insisted reports of widespread cultural breakdown in Australia's swim team in London were off the mark, but admitted he was a changed man since the scandal blew up.
"I started to believe my own press a bit, started to think I was The Missile rather than just myself," he said.
"I am trying to be relaxed and humble, not beating my chest trying to be the alpha male of the team.
"It was actually harder for me to put on that act (before London) than being myself," he added.
"So I feel really comfortable with how I am conducting myself around the pool and my teammates -- hopefully people are taking note of that."
Magnussen is looking for redemption at this year's worlds after missing out on the Olympic 100m freestyle title by just one-hundredth of a second behind American Nathan Adrian.
He admitted he was devastated.
"While this world championship is really important to me and I'm defending my world title, I want to be an Olympic gold medallist," he said.