For Barry Swan, it goes back to when he cradled his grandfather, who was dying of black lung disease, and decided to change his life.
He was just 19, and his grandfather, past 60 but not old enough to die, was in the grips of pneumoconiosis, the horrendous disease which claimed so many lives of the men who went before them.
About eight per cent of the workforce were "dusted", they called it - aged before time, old faces on a young man's body, shortened life expectancy to match.
Coal mining is often a family business (except you don't own it), and Mr Swan is part of a long line. His grandfather, his father, and his sons, all are, or have been, underground.
"I sat the night with him - I knew what that disease did," Barry said.
"He was 25 years younger than I am now. I saw him struggling to breathe - he had a heart like a lion, but you could hear the wind whistle through his chest. He lasted the night but the with the sun, he went.
"That was the real impetus to me. I pledged myself that if ever I could get into a position where I could help improve the life of coal miners, I would. So I did."
Barry (whose birth certificate is the only one that ever uses his real given name, William), had taken an apprenticeship at the steelworks, but before long he decided to work his way into the coal industry.
He started at South Bulli, as his grandfather did in 1924. Before long it became clear that a career in the union movement was the path for him. He was leadership material, and he rose to become the general secretary of the Miners' Federation Australia-wide. His OAM is for services to the coal sector, and for him the work on black lung was the peak.
But for drama it's hard to beat the 1982 Kemira mine sit-in, where 30 workers stayed underground to protest against job losses. Swan was front and centre, including when the workers stormed Parliament House to try and talk to then-PM Fraser. It worked, the talks with Fraser gave Barry hope jobs might be saved. He was wrong.
Over the years he was a board member of the Joint Coal Board, as well as the chair of its dust committee.
Barry's a keen golfer, and his research helped the Russell Vale Golf Club's project to name each hold after a local mine, with information signs at each tee. He keeps his vocal chords in shape with the Lamplighters Choir.
"All the way through, at every turn, I had the support of the rank and file of the Miners Federation," he said. "They might not have agreed with me, and I might have made some blunders, but they kept voting me in, and for me that was gold, to have the respect of your peers."