He could continue along the path he was travelling living an unhealthy lifestyle, or he could make a change.

He took the latter option.

Five years later and Duffy has completed a host of endurance events, including a full ironman triathlon.

Read more: Grida ruled out of Melbourne United showdown

The 48-year-old topped that effort over the weekend, finishing his first ultraman triathlon.

The event saw Duffy swim 10 kilomteres, ride 420km and run 84.3km across three days.

It's a competition that left him physically sick at times throughout the weekend, but the landscaper said there was no chance he would quit.

"No one who does these events quits," Duffy said. "There was a guy who positioned himself on top of one of the climbs with a box of donuts, offering a donut to anyone prepared to quit. No one was taking a donut.

"We'd put in too much work. The people who were there, the only way they come off the course are if you're dragged off or an ambulance takes you away. I was never quitting."

Duffy has already turned his focus to his next event, a 6500km cycle that will see him ride from Cape York in Australia's north to Wilson's Promontory in Victoria.

While many are starting to slow down as they approach 50, the endurance athlete feels healthier than ever.

"I feel better now than I did during my 30s. I was eating wrong and drinking too much but I had a change of outlook. It was time to invest in myself. I'm just an ordinary guy who likes to work hard and challenge myself and I'm doing what I can while I can still do it."

We depend on subscription revenue to support our journalism. If you are able, please subscribe here. If you are already a subscriber, thank you for your support.