When Aaron Richardson broke his leg during a footy game in 2008, his high school coach Samantha "Sam" Naudin came to the rescue.
With his offshore job to consider, the risk of injury was too great for the then 23-year-old to play on.
Having played football since he was a teenager, he was at a loss until Ms Naudin, who at 47 lost a long battle with cancer in January, suggested a switch to triathlon.
To honour her memory, the international triathlete will swim from Rottnest to Cottesloe on November 23, setting off at midnight.
"I'm one for challenging myself," the Hamilton Hill triathlete said yesterday. "I don't like following in the footsteps of others.
"Doing the swim at night is something that no one's tried."
He says Ms Naudin remains his inspiration. As a high-profile campaigner, she raised thousands of dollars for breast cancer research.
Richardson met her at school in Queensland, where Ms Naudin saw his potential as a triathlete.
"When I was supposed to be doing schoolwork, she had me swimming laps or running down the oval," he said. "She was always pushing to get the best out of me from day one."
After learning of Richardson's injury, Ms Naudin pitched a return to triathlon as his best option.
"I couldn't play footy again because I didn't want to break my leg again and not be able to pay the mortgage," Richardson said.
"The last thing she said to me was, 'Race, please get to New Zealand and race. Do that race for me and I'll be there with you'. That was in December last year. She passed away in early January."
Support crews on surf skis armed with shark shields will patrol the water as he swims.
When he reaches land, a barbecue will be held at Cottesloe beach and a champagne breakfast at Cottesloe Surf Life Saving Club.
All funds raised will go towards meeting Richardson's target of $30,000 for Breast Cancer Care WA.
To make a donation for the swim, go to breastcancer.org.au.