So when he runs a marathon in the Newcastle Herald Hill 2 Harbour on Sunday, it'll kind of be a normal day.

Gary, now 43, has run 15 marathons at proper events. This includes six marathons, five 50-kilometre races and four 100-kilometre races.

"I'm fitter now than when I started running when I was 35," he said.

"I run three to four days a week. I've been running 100 to 150 kilometres a week for the last three months. On the weekends, I'll knock down 80 kilometres - probably 40 on Saturday and 40 on Sunday."

He says he doesn't feel much pain during the runs.

"At the start it was hard, but I'm pretty fit now. I'm used to it," he said.

"I think my mind is pretty strong. My body says stop, but my mind says keep going."

He takes a few rest days in between the weekends, while also working as a lawn mower.

While running two marathons a weekend, he said the Sunday run was always harder.

"You get your endurance running the next day on heavy legs. You get gains running on fatigue," he said.

He's been going through a pair of running shoes each month.

"You get holes in them or the tread starts going on them," he said.

All the marathons he's been running are preparation for running 100 kilometres in the Ultra-Trail Australia event in the Blue Mountains in May.

Before he found running, he spent eight years in jail for robbery and break and enter offences to fund gambling and drug addictions.

Greg had a difficult upbringing. He was adopted at age three.

"My mother had schizophrenia and my dad had bipolar. They couldn't look after me," he said.

This left him with a lot of hatred and anger. Running helps him process those deep feelings.

Asked what jail was like, he said: "It was pretty tough losing your freedom and hanging around with tough people".

"You're always looking over your shoulder."

Running gave him his freedom back.

"When you run, you release a lot of trauma from the past," he said.

"I get the runner's high. The euphoria and adrenaline."

He's been blessed by not having experienced any injuries, despite running thousands of kilometres in eight years.

For Sunday's event, he'll be raising money for the Samaritans.

"They helped me when I was down and out. They saved my life, so I want to give back to them," he said.

"Whether you raise $5 or $50 million, it's the principle. When you run to break records, you lose the fun of it. When you run for a cause, it makes it more special."

Asked if he had some words of wisdom for others struggling with life, he said: "There's light at the end of the tunnel".

"Go and get a pair of running shoes or find a hobby or sport.

"Channel all the negative energy into positive energy."

To contribute to Gary's cause, visit chuffed.org/project/running-for-recovery-point.

Long distance running has many challenges. One of the biggest challenges is where to put your house keys.

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