"I just turned 42 last September. I guess I'm sort of a numerical person and so I thought 'I'm 42 and a marathon is 42 kilometres'," the Kingston resident and project manager said.

"As a goal to set myself, during the year that I'm 42, why don't I try and run a marathon?"

Mr Porter signed up to an online training program, and runs regularly at least three times a week. For the past 15 weeks, Mr Porter has stepped outside and run, no matter what threatened to get in the way.

"During my training program I've actually been travelling for work, so I've actually had to fit my training runs around my travel," Mr Porter said. "I've done it in Thailand, Tokyo, the US, Canada and New Zealand; I've actually been travelling a lot over the last little while."

However, Mr Porter often takes his runs alongside the Kingston foreshore - ranging from an 800-metre dash along Dairy Road to a massive 32-kilometre loop around the Molonglo River.

Mr Porter and his wife also frequently join parkrun events - organised and timed five-kilometre runs along set routes, which are held around the world.

"Straight after the marathon we're actually flying to Italy for three weeks and we're going to do two parkruns while we're over there as well," he said.

Mr Porter is no stranger to the world of endurance sport, having a wealth of experience in the sport of rogaining - a tough orienteering marathon that can last as long as 24 hours or more.

With entries in the World Rogaining Championship and a South Australian Rogaining State Championship under his belt, this isn't his first endurance rodeo - but it's an entirely different bull to ride.

Mr Porter is upbeat about his participation in the festival, but he's well aware that it's not going to be all plain sailing.

He had a knee injury two years ago while training for a South Australian ultramarathon, in which he was unable to take part. This is his first major run since then, and he suspects the nagging issue could cause problems.

"I think the thing I'm most worried about is that my legs are going to give up at the 32-kilometre mark," he said.

A bad wheel has left Mr Porter with no shortage of motivation, from the support of his wife - who is running the half-marathon - to his personal marathon playlist of pure '80s and '90s gold, including tracks like Video Killed the Radio Star and a steady supply of Blink-182.

However, Mr Porter's real motivational weapon is his unique "42 at 42" approach.

"It's actually an opportunity to reflect on the 42 years I've had. As I'm doing the run, as I pass kilometre 18, I might look at my little list and say 'that's right! That's when I was doing year 12'. That can be a way to take my mind off of the pain my body may be experiencing and take a trip through memory lane at the same time," he said.

Mr Porter's advice to others is to set a target.

"What I found in my training is that anyone can go out and walk 42 kilometres ... It's about what pace you want to set," he said.

"I would be really happy if I can finish in three-and-a-half hours - but I'd be happy to finish it in under four."