Matthew Mitcham: 'Platform king' to 'Queen of the World'

One minute he was at the top, looking down. King of all he surveyed.

The next thing he knew, the bottom had fallen out of his world -- again.

Diving is predictably a sport of highs and lows, but for Matthew Mitcham it goes so much deeper than that.

The first openly gay man to win an Olympic gold, he has learned to once again love the life that has contributed to his darkest moments.

"As a teenager, I felt like I dropped everything for diving. I put all my eggs in one basket because I felt like it was my ticket to being special," the Australian tells CNN's Human to Hero series.

And it did make him special.

Having made headlines around the world when he came out before the 2008 Beijing Games, his profile took a quantum leap when he shocked the home favorites and claimed the 10-meter platform title with a record single-dive score.

But that adulation -- he was honored with his face on an Australian postage stamp -- quickly turned to despair as he relapsed into the depths of the depression that had led him to retire two years earlier aged just 18.

"My self-esteem started to plummet again after Beijing," he recalls, having been the first Australian diver to win Olympic gold since 1924.

"I had the belief that the people only liked the medal and that I myself was inconsequential.

"Diving has been a constant part of my life, but it hasn't always been the most positive part of my life ... but somehow I'm still here and I'm still doing it, so it has been an affair of highs and lows."

Having overcome his well-documented personal problems -- as laid bare in his book "Twists and Turns" -- Mitcham is now heading into a new phase of his life.

Next week he begins what could be the last major competition of his diving career, the Commonwealth Games in Scotland.

He won four silver medals at Delhi four years ago, and is looking to complete a notable collection along with his Olympic and World Cup golds -- especially after failing to reach the final in his 10m title defense at London 2012.

"There's mixed feelings of excitement and a little bit of sadness because it might be time to move on," the 26-year-old says.

"I'm not sure, I haven't made any decisions but you know, getting older, looking at the rest of my life, I'm starting to consider that stuff now."

When Mitcham triumphed at the Beijing Olympics, he was afforded the ultimate kudos by Australia's LGBT community -- being named "Chief of Parade" for the Mardi Gras festival in Sydney the following year.

"That was super cool," he says. "I felt like Queen of the World."

It appealed to the performer in him -- and he has already started branching out into the entertainment world with a cabaret show based on his 2012 autobiography, which details his problems with drug addiction as he struggled to deal with his success.

He sings, plays the ukulele and recounts his life story.