Starting August 31, Nedd will clock off his work as an apprentice electrician and pound the pavement for 42km to raise funds for the Australian Red Cross.

Running is something the former Platypi player has only picked up since his relocation to Sydney to take up his trade.

"A year-and-a-half ago I couldn't run five kay in five-minute pace," Nedd said.

"But I started getting fitter and I really enjoyed it.

"I reckon it might be my life after this, I love it. I just absolutely love it."

And now he's decided to run to raise funds for the Australian Red Cross to direct to homelessness services.

"Every Tuesday when I venture into the city for TAFE I always see homeless people doing it tough and sleeping rough," he explains on his Red Cross fundraising page.

"Every one of them have a story and some are the most beautiful people, everyone deserves to at least have a roof over their head and food available.

"I feel like I'm really in a position where I should be able to help," he told the Advocate.

Normally that's through something immediate such as food, or his hoodie, but he's hoping his marathon effort will draw support to provide services as well.

"I just like what they do," he said, hoping the funds will provide homeless people with a place to stay safe or help someone living in poverty have some certainty about their next meal.

"I'm a bit of a nut," he admits, "but I want to see how far I can challenge myself."

The 21-year-old knows the mental challenge could well be the biggest part of it.

Earlier this month he challenged himself to a 100km run, from Randwick to Palm Beach and back, and 58km into that he was really starting to wonder why he'd decided to spend his weekend like that.

"If your why is bigger than your reason to quit, then you won't quit," he said.

And this fundraising challenge is a pretty big "why" for Nedd.

"I know what what I'm up against," he said.

"I've been training a lot to get a base to work off."

Nedd has several 42km tracks he'll rotate, ranging from doing 12 laps of Centennial Park to powering out 42km on the treadmill.

He can run a marathon in three hours, but he's planning to pace himself and allowing four hours to ensure he gets through the 50 days.

Friends and sponsors have come on board to offer practical support such as free physiotherapy, nutrition, and meals cooked by his mates.

When Nedd spoke to the Advocate he'd run 14 half marathons in 14 days, he was planning to continue his training for another week and then back off until his official start date.

To support Nedd, go online to https://fundraise.redcross.org.au/fundraisers/neddbrockmann