He knew what his night would look like if he got out of the car and went inside: he'd drink too many beers, smoke too much weed and pass out on the lounge before he woke the next day and did it all again.

"I thought, I'll be lonely, I'll be miserable. I don't want to do it again. I've been doing it for too long."

Instead, he called his parents and admitted for the first time that he needed help to kick addictions to alcohol, cannabis and speed which had dominated his life for the best part of a decade.

"Every day when I woke up I'd think, 'I'm not going to drink today, I'm not going to use today'. I'd swear black and blue.

"I could get to about lunchtime or early afternoon and something would shift and then I'd start to make excuses like I was going past the bottle shop, or it had been a long day and I deserved a couple of drinks. But it was never just a couple."

His addictions took a physical and emotional toll. He felt his world closing in on him as he tried to fill a deep and lasting sense of loneliness with drugs and alcohol.

"It was a real life of isolation. I was just existing, I wasn't really living. I was working just to feed my habits."

"You start to do things you're not proud of and you start crossing over your moral standards. You wake up in the morning filled with guilt, shame and remorse.

Mr Veenker spent 28 days in rehabilitation in 2012 and vowed to take up running, which he had enjoyed as a child, as part of his discharge plan.

He had a short term goal to get fit and a long-term goal to run a marathon - but admits it was hard at first.

Soon he realised pounding the pavement was key to his healing.

"Instead of grabbing a beer or smoking a pipe when I got home I'd go straight out for a run. I think it gave me more of a natural high, I had these little milestones and [personal best]'s."

Next month Mr Veenker, 36, who now works in community health as a drug and alcohol counsellor, will take on the Canberra marathon as part of this year's Australian Running Festival.

Two years ago he ran the Melbourne Marathon and soon set his sights on an even bigger goal - to run a marathon in every state and territory.

"I've got this newfound sense of freedom and a real zest for life," he said.

"My relationships have improved and there's a real honesty in my life now."

The Australian Running Festival is on the weekend of April 9-10, with The Canberra Times Canberra marathon on the Sunday. To register go to runningfestival.com.au