The Kokoda Trail is infamous for its 96km of steep terrain, made worse by unrelenting humidity, mud and rain. But that doesn't worry Col Reynolds, 81, who'll be tackling the trail in a year's time.
The founder of The Kids' Cancer Project isn't just doing the trail one-way, either. Once's he's finished, he's turning around and going straight back, which means almost 200km of gruelling walking in 18 days.
"Doing Kokoda back-to-back has never been done by someone my age," Col says proudly from his Townsville home.
"But I'm not doing it for the world record - I'm doing this for the scientists and the kids who are battling cancer."
Col is no stranger to ambitious fundraisers. Since he founded project in 1993, he's done everything from shave his head to drive a bus down the east coast of Australia.
In all, he's helped his charity raise more than $50 million for childhood cancer research over 27 years and earnt himself an Order of Australia Medal in 2000 for his amazing efforts.
He hopes to bring in hundreds of thousands of dollars from next year's trek.
To make things even more challenging, Col also has to learn to walk on a new knee - he had his second knee reconstruction done in early May.
Ever the optimist, he sees this as a help, not a hindrance.
"I've actually walked Kokoda before - I did it four years ago, but just one way," he says.
"Back then, I had my original knees, and there was very little cartilage left - so it was basically putting bone on bone.
"When I finished Kokoda, I still felt so good that I wanted to do it all again. So I figure next time round, with two new knees, a back-to-back trek will be peanuts!"
Col is itching to get training on the hills of Townsville and "beat the young ones to the top", but for now it's all about rest and rehab. He knows that soon enough he'll be doing hours of walking and hill climbing a day with a 10kg pack on.
In the meantime, his determination has inspired a few of his medical team to join him next year, including his orthopaedic surgeon Dr Levi Morse, whose son Orlando battled cancer at eight months old and survived.
Col jokingly calls himself a "blockhead" for attempting to pull off Kokoda back-to-back at his age, but he understands exactly how important it is to fundraise in a creative, inspiring way right now.
"With the coronavirus, charities like ours have had a lot of trouble raising funds. Which means scientists' funding is in danger.
"You can't just suspend research for a year. That research may have been going on for a decade, and you'd lose everything."
Col has a laser focus on the importance of research and his role in supporting it.
"When I started fundraising in 1993, kids' cancer research just didn't have money - it was a room in a hospital with a few scientists, a Bunsen burner and a basic microscope.
"In my time, I've seen the difference money makes - it means better survival rates and better treatments with less side effects. But I won't rest until we've found a cure."
For several years before starting The Kids' Cancer Project, Col had been taking young cancer patients out on day trips, using his experience as a tour bus driver to bring some much-needed relief and excitement to sick kids and their families.
But in his own words, it wasn't enough. "I went to too many kids' funerals, and I just thought 'Bugger this - I want to save a kid's life, not just take them out for a trip'."
It's the kids that make him do his knee rehab with gusto, so that he can get ready for all 200km of Kokoda in a year's time.
"I've promised a cure to so many kids who are no longer here," Col says. "I have to meet that obligation; I have to keep those promises."
You can help support Col on his epic journey and kids with cancer with a tax-deductible donation. Call 1800-651-158 or visit thekidscancerproject.org.au