And what that drove the former Kinross Wolaroi student to achieve is nothing short of remarkable.

The Forbes boy ran 50 marathons in 50 days, all the while continuing to work full time in his trade in Sydney.

He completed more than 2100km since August 31 - more than some people drove in their cars last month - and in doing so raised more than $85,000 for Australian Red Cross - that was his reason why.

Mr Brockmann's efforts have been to aid the plight of those people living homeless in Sydney.

"It breaks my heart living in this beautiful part of the world that some people don't even know where there next meal will come from or worse, don't have a roof over their head," he wrote after completing his 50th marathon on his Nedd's 50 in 50 page.

"Please, just be grateful for what you've got and the people you have around you.

"If you can, lend a hand, say hi to someone you wouldn't normally, just smile. Guaranteed to make someone's day."

Mr Brockmann shared to his public Facebook page that running 42.2km every day has taken its toll on his body and he's battled through injury, but last Monday night he pumped out his 50th marathon in 2 hours 53 minutes - his first sub-three-hour time.

"How did I wake up every day and go again? I did it because I told myself I had a job to do and it was literally non negotiable," he continued in one of his final posts.

He said community spirit has driven him throughout the incredibly journey.

"Community and being connected is everything, the money I've raised thanks to all you legends will do great things, but the most important part of all this is that it's brought people together and has turned a whole lot of people's lives around," he wrote.

To those who have contributed to his fundraising target, he wrote, "from big to small, I appreciate every single dollar".

On Nedd's fundraising page, Australian Red Cross advises: