Captain Australia, as he's better known, is making the roughly 1800 kilometre journey not just to help with his own mental fitness, but also for kids fighting cancer.

"It started for me with personal healing," he said, standing at a gravel rest spot between Clybucca and Gladstone on NSW's North Coast (about 480 kilometres from his starting place).

"I had stage four cancer in 2016 and was given six months to live.

"I had a 40 to 60 per cent chance that chemotherapy could shrink the tumour, make it surgically manageable or completely get rid of it.

"I got lucky and it did."

While he was able to survive the cancer, Simon explained the mental barriers were still there.

"I couldn't bounce back, I wasn't thriving, I was slowly slipping into existential crisis and I remembered a time as a child I walked from Brisbane to Sydney to live with my grandmother," he said.

"It was an escape from a bad domestic situation and it took me towards hope and that muscle memory made me think I needed to take another big walk.

"Then I realised since I was going to do a big walk I should super hero up for science - I've got my Captain Australia mask and it's all in support of The Kids' Cancer Project."

A noble choice of charity, the inspiration came from Simon's own experience sitting in chemotherapy waiting rooms, watching children prepare for treatment.

"It's heartbreaking, it's wrong, it's not on," he said.

"So with that project there's two dimensions; personal healing, repair and rebuild and helping the charity out."

With the pacific highway roaring down the east coast, the trek has changed significantly from his first walk as a child however Simon's not limiting himself to the long straight connecting Sydney and Brisbane.

"I've gone down the highway, it's a bit iffy at times," he said.

"I'm sleeping rough on the side of the road with a hammock and tarp there and it's constant barrage of noise so it's nice to get onto country roads and the beach.

"The compromise there is you're making less distance in the day and every time I make a choice that lengthens the journey I'm aware that it's taking me further away from my three kids."

"I miss them something fierce, I could've gone straight down the motorway and it would've been much shorter but I chose different routes because I'm not done with my healing yet, a lot of that's letting go of grief and thoughts you haven't processed and releasing it.

"Sometimes I've been walking down the beach sobbing because I'm releasing an emotion I had pent up inside for a few years.

"At this stage though I'm more or less at peace now, I could go home now, but it's mainly for the charity at this point, pushing through and saying what I'd do otherwise I'd rush home to my children."

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While being away from his children has been one the toughest aspects of the walk, being a better father provided more ammunition to start the journey.

"One of the things that motivated me to fix myself was I thought I was under-performing as a dad and that's one of the most important jobs in the world to me.

"It's ironic because my solution to fixing that was to go away but I'm looking forward to getting back and cuddling the kids again."

After sleeping between Clybucca and Gladstone last night (January 13), Simon will travel to Gladstone, Belmore River, Crescent Head and then walk via the beach to Port Macquarie, all on the NSW North Coast.

The next leg will then work out itself with "a lot of country between here and Sydney."

While there's been some beautiful spots along the way, it's the people he's met that Simon cherishes the most.

"In Ballina I was really missing my kids then I met this woman called Jo," he recalled.

"I was sitting on a stone fence having this little sook, she gets up sits next to me and says, 'G'day you want a Kombucha?'"

"We exchanged stories and she was just lovely.

"Since then she's turned into the Alfred to my Batman - we've stayed in touch and she's been giving me suggestions about where to go.

"Getting out of Ballina is a bit sketchy so she gave me a path with a similar amount of distance.

"I winded up in a cow paddock, followed a fence line, opened and closed gates as I went, eventually I got to where I needed to be but it was like a childish adventure - jumping fences and stuff - last year the idea of jumping fences was laughable."

With a Facebook page, Captain Australia's Big Walk, the journey has attracted a significant following, possibly born out of the past three years.

"Everyone has a COVID fatigue, everyone has been isolated and they love seeing these examples of hope and people being kind," Simon explained.

"When someone puts me up and says they have a bed for me tonight, people watching love it, they get something from it and I couldn't have anticipated that at all.

"We've become a bit distanced from that basic idea that we are all kind, we are all trying to do the right thing and we are all good at heart.

"I believe that's a fundamental truth, one in every 200 people is an evil bastard but most of us are kind and decent.

"That's maybe a third dimension to the walk now, that sort of inspiration of it."

With a long journey still to go Simon recounts, through a dance, that motivation has come from unexpected sources in Martin Gaye and Powderfinger.

"There's no great trick (mentally), for any long distance walk you let your mind go somewhere else," he said.

"I find when it does, other stuff comes in and I get a bit of Motown - 'ain't no mountain high enough, ain't no valley low enough'.

"I'm walking along and continual Motown will flood in for three hours until I find myself signing along.

"My Happiness came into my head and I couldn't get to the verse because there's this line; 'how could I do this to you right now, you're over there and I need you here', then I'm starting to think about missing my kids and it's about the happiness of coming home.

"These songs just jump into my mind - I need a personal soundtrack to walk around.

"Mine is just jumping into my brain as I walk, I'm emptying out a lot of garbage and just trying to be serene but in that silence a lot of random music jumps in."

Asked on whether he compares it to a walking meditation, Simon said there's certainly a difference.

"Meditation has this idea that it's taking you to a higher place and that you're achieving some sort of spiritual awakening but I don't know if me having Aretha Franklin jumping in my brain is a spiritual awakening," he laughs.

Donations to The Kids' Cancer Project can be made here or by stopping Captain Australia on his walk and using the QR code.