The world watched as Nedd Brockmann took the final steps on a 1000-mile journey, tore aside the finish banner and hugged his mum.

The bloke from Bedgerabong had lapped the Sydney Olympic Park athletic centre 3760 times in 12 days 13 hours and 45 seconds to raise funds for people experiencing homelessness.

He'd held nothing back - either in the effort itself or in the images streamed to the world of just what he was putting himself through to complete the task he'd set - and an inspired Australia has now donated $3.5million to the cause.

"We're so much more capable than we think," Nedd said in interviews streamed on TikTok LIVE in the hours afterwards.

Nedd had been preparing for the challenge for a year, following on from his run across this vast continent.

With the task conquered, he revealed he'd suffered an injury in the lead up that hampered the last months of his training, and that injury as well as others flared up as he opened his fundraiser effort running more than 160km a day.

The final stages of the 1600km-plus effort were completed walking for 200m, then hobbling for 200m, in Nedd's words, but he completed the task he'd set.

Physio Alex Bell from The Running Room testified the injuries would sideline most people.

"I'm certainly walking away from this thinking there's so much more possible in all of us," he said. "I'm so proud, grateful to be on the journey but you're a special human doing special things."

With Nedd's run streaming on TikTok LIVE, the messages of encouragement came in from all over the world and donations from more than 40,000 individuals as well as corporate donors.

"I'm just so, so grateful that this life pursuit of mine - in wanting to push myself to the absolute end - just to show people we live in this world where we're so much more capable than we think," Nedd said.

Keep showing up has been his message since his first massive fundraiser effort.

"If it doesn't go to plan, divert, go the next thing, stick with it, see it through because you said you were going to do it," he said.

Have a reason bigger than yourself to push for is critical, and that's where Nedd's challenge to everyone else comes in.

Nedd set a challenge to the country as well as himself, with Nedd's Uncomfortable Challenge launched October 20.

You don't have to run, you just have to set a challenge - something that pushes you out of your comfort zone - and do it for 10 days.

"Have a crack at life - we only get one, that was the hope," Nedd said.

A total 6870 people had signed up online for their own challenge over 10 days.

Nedd described the 12 days he'd been on the track as the toughest of his life - and the same was true for his mum Kylie who was there around the clock, and together with his dad Ian holding the banner at the end.

It was, she said, an incredibly emotional moment.

Through the run, the fundraising dollars kept creeping up on the big screen at the track, and while Nedd said he couldn't possibly have been more motivated than he was it was certainly special to see it tick over to $1 million.

"It's a nice way of going wow we're actually making an impact," he said.

"When I hit the million that was a special moment for me and the crowd that was here was really cool, really special."

Nedd paid tribute to everyone who got him through the run.

"Without the support crew, I wouldn't get it done, I'm grateful for every single one of them," he said.

He also thanked all those who have supported Nedd's Milk, available locally.

In the first year of operation the business has been able to donate $200,000 back to Mobilise.