At the age of 50, Brooks is back in Australian colours to compete in the World Triathlon Championships on September 13 and says he's in the best shape he's been for a long time.

The swimmer, who fell off the rails and spent years battling the booze, has turned vegan and shed a massive amount of weight to regain fitness.

Brooks is competing for Australia in the 50-54 year age group sprint distance, which is a 750-metre swim, 20-kilometre ride and a 5-kilometre run through London's Hyde Park - essentially the same course as the London Olympics - and is expected to attract 250,000 people over the weekend.

Brooks, part of the 1980 Moscow Olympics gold medal-winning swimming relay team, went on to become a high-profile Channel Seven presenter, before fleeing Australia with his wife Elle, son Levi and daughter Brooke in September 2010, after multi-million dollar business deals collapsed amid claims and counter claims of fraud.

Brooks was attacked on the Gold Coast by two men and his business partner at the time, and claimed his life had been threatened which forced him to go into hiding, first in France and then in England.

The former swimmer is now taking legal action against Channel Nine's A Current Affair for defamation over stories it ran on Brooks' business collapse.

Since the collapse of his business world, Brooks has faced tough times living in England and was even forced to busk on the streets to earn enough money to feed his family.

While he battles to clear his name, he says life is still tough, but he says getting himself back in shape has helped give his life new focus.

"In terms of how I'll go at the world champs I have no idea," he says.

"I'm truly just delighted to be a part of the Australian team and when I got my uniform in the post just recently it felt just as amazing as it did 29 years ago.

"If I was to finish in the top 10 I'd be absolutely over the moon, but to be brutally honest I don't care where I finish and I know that seems strange to say, having been such a fierce competitor my whole life, but the biggest battle I've had to face has been overcoming the reckless need to self sabotage, which I have done.

"The fact I'm even on the start line after where I've come from is a massive win for me.

"The only win I really care about now is my upcoming court battle with Channel 9 to clear our family name of all the rubbish they have accused us of, which is about to heat up in the court - finally - that's going to be more of an Ironman than a sprint but at least I'm in the best shape of my life for this one and I'm ready to go the distance that's for sure."

Brooks says getting involved in triathlons has saved his life.

"I've always had such a life of excess and have never been able to just moderate," he says.

"Whatever I do I tend to have an all or nothing approach, whether in the past it's been drinking myself to death, eating poorly or just generally leading an unhealthy lifestyle, I've always managed to go really hard at it whatever my lifestyle choice.

"Fortunately for me I've had a massive wake-up call and now I accept the way I am and channel my all or nothing approach to being happy healthy and fit for life and triathlon is a by-product of that I suppose."

Brooks says there's a huge difference between being fit and being healthy.

"I've been pretty fit for quite some time now but not necessarily healthy. I'm predominantly talking about diet in this case, as just recently I completely switched to a plant based only lifestyle or for want of a better word I became vegan," he says.

"It took a couple of weeks to adjust but now I feel totally amazing and literally can't remember feeling any better in my life, and I've never enjoyed being involved in sport at any time as much as I am now, including back in the Olympic days.

"I think if I'd been as diligent and focused back then as I am now I would have been a great swimmer, not just a better than average one.

"Now I could just swim masters and be pretty successful I suppose but I wanted to get totally out of my comfort zone and try something that most people thought I wouldn't be able to do, because at the end of the day I'm completely the wrong build to be a successful triathlete because of my size, but I don't care I just love it and I'll push to be the best I can be," he says.

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