When Jason McNamara started running, he would barely make it a couple of hundred metres down the road before his body began screaming at him.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
He was 33 years old, and weighed 117 kilograms and by his own admission, did only what he needed to get by in terms of exercise.
But in the space of only three years, the public servant would shed more than 40 kilograms and become one of the small number of Australians to ever complete a marathon.
But it wasn't losing the weight which presented the biggest challenge, the Gordon-based father-of-three reckons.
"The weight loss was the easiest part, the mindset was the hardest part," Mr McNamara said.
He fell into running while seeking a way to get his ballooning weight under control.
"I could burn more calories running so I started jogging," Mr McNamara said.
When he first began, he couldn't run a kilometre without stopping to walk.
While he always entertained the notion he might one day be able to run far enough to enter a race, he was riddled with self-doubt.
"I had this little dream in my head that I want to compete in just one race, any race would do. I didn't think it would be realistic that I could run the whole thing but I thought I'd give it a shot anyway."
In the end he learnt to switch his doubts off and listen to the "drill sergeant" in his head.
"It's like a muscle, your mind. Once you flex it, and keep building on it, it becomes stronger and stronger and stronger," he said.
"I have a very stubborn nature and that ended up kicking in my head after a while which was good. It's like a drill sergeant, telling me to stay focused, stop making excuses."
He found once he was in a routine, he'd be up and out the door before he even realised what he was doing.
He would run everywhere – to work in Woden and even to the Tuggeranong shops to grab a coffee.
He finished his first marathon at the Canberra Times Australian Running Festival in 2015 and has been unstoppable ever since.
Mr McNamara runs scores of kilometres every week and will again take part in the running festival in April.
The joy of seeing his wife and children waving him over the finish line in his first race, the Canberra Times fun run in 2013, has stayed with him and motivates him when he hits the wall.
He never intended to fall in love with running but now he said it's a part of his life.
His wife runs in the mornings and he runs in the evenings, after prepping dinner at home.
"I stop running for three days and I'm like 'I need to go for a jog'," he said.
He said people need to stop thinking about what they can't do and focus on what they can.
"If you start thinking about the reasons you shouldn't do stuff you become fixated on that," Mr McNamara said.
And having a good incentive – like a coffee – waiting for you at the end always helps.
"You don't want to break all of your habits," he grinned.
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