He was struck down by the black dog after the traumatic birth of his first child, suffering from post-traumatic stress and being diagnosed with depression and anxiety.

Mr Greenwood said the mental illness, which affects one in five Australians, crippled his ability to function.

“All my thoughts went back to when I lost my mum when I was young, and my system shut down. People were talking to me, but it could have been a different language,” he said.

He is raising funds for the Black Dog Institute but said the journey from the Sydney Opera House to Parliament House provided its own symbolism.

“There is hope and you can push through,” Mr Greenwood said.

“That’s what this marathon is all about. It’s not a sprint – you have to keep plugging away.

“You need to take one step at a time, and with others walking alongside you can get through to the other side.”

Mr Greenwood planned to stop off at sporting clubs along the way and encouraged people to join him to tell their own personal story.

Each story was to be translated as a drawn hand print on a scroll, which will be presented to representatives from the federal Department of Health on Friday.

“Men in particular don’t like to talk about their mental health or things that make them look humble, but it’s a conversation we need to have,” he said.

“Resilience plays a huge part in the mind, and when I hit a wall I didn’t have that resilience or physical fitness to counter what I was trying to fight.”

If you or someone you know is in crisis please call one of the following national helplines:

LIFELINE COUNSELLING SERVICE 13 11 14            

SUICIDE CALL BACK SERVICE 1300 659 467 (cost of a local call)