“I started off doing 30 and 50-kilometre runs and I got sucked in. I just love the trail running,” he said.

The distances he set himself steadily increased in the months and years that followed. John, 56, was addicted.

The prospect of running 100 kilometres, as he will do this weekend, has become a challenge he relishes, rather than backs away from.

“I’m kind of competitive. But at my age, I’m not fast but I can go for a long time. It’s a different style of running,” he said.

“If you’re running 21, you have to go flat out for 21. But if you want to do 100, you have to go at a steady pace for the whole 100.

“For me, that seems to be easier. I can go for longer. I don’t have to go flat out but I have to go for a long time.”

John will be among 70 athletes braving one of the toughest events on the Australian ultra-marathon calendar on Saturday, the Great Ocean Walk 100 (GOW 100).

The 100-kilometre test asks competitors to run from Apollo Bay to Port Campbell along the world-renowned Great Ocean Walk trail.

They set off at 6.30am, carrying water and food, along with mandatory safety gear — mobile phone, map, first-aid kit, space blanket and torch.

John clocked 13 hours, 43 minutes and six seconds last year. 

His aim is to finish, but a greater sense of satisfaction will be in setting a new personal benchmark.

“There’s no better feeling than when you go into a 100-kilometre race and you cross the line and there are people you don’t know clapping and cheering,” he said.

“You have a big smile on your face. You’re exhausted but you’re really happy, especially if you’ve done it hard. That smile will last for a couple of days.”

His journey to the start line started six years ago, when he joined Warrnambool Athletics Club (wac) and discovered he had a knack for running long distances.

John has been a WAC member since, winning the president’s award last month, and spends his spare time pounding the pavement around his home.

His mantra for Saturday is “you don’t want to be the hare, you want to be the tortoise”.

“I think (ultra-marathon running) came at the right time. As you get older, you fit into the longer events better,” he said.

“When you’re younger, you’re fitter. You want to go fast. When you can’t go fast any more you start to want to extend the distances.”

Great Ocean Walk 100 director Andy Hewat believed trail running had enjoyed a surge in popularity in recent years.

He said the 2014 event reached its entry cap of 70, set by Parks Victoria, within an hour, such was its appeal in ultra-running circles.

“I run a few of these ultras in Australia and a few in the States. In terms of terrain, it’s up there with the best you can find,” he said.

Hewat said he created the GOW 100 to give something back to a sport.

“I’ve competed in ultra-marathons for 15 years and it was really a case of giving something back to the sport and contributing,” he said.

“I do this in my spare time. It’s not a commercial interest. It’s really just a case of applying what I’ve learnt and what I know to an event.

“From the feedback I get, it’s appreciated. It’s put on by runners for runners, they can tell the difference.”

Saturday marks the sixth edition of the GOW 100. Bushfield runner Nicole Barker is also among the field of 70.