Phil Yeardley, 22, set a goal of running 100km on the Caledonian track, 250 laps of the 400m-circuit, on Saturday.
He did it, in just under 16 hours, but admitted it was not easy.
"I wouldn't say easy. It was tough. That last 10km was so tough," he said.
"The body was cramping and I was feeling like vomiting and stuff. But I just had to force myself to get it out of my system and then chunk on for the last 10 laps."
He had plenty of company for his charity run.
"It was insane. The first lap was just by myself and then the rest of the 249 laps, I had at least someone running with me every other lap."
He said a Danish tourist came along right at the start and proceeded to complete the whole rest of the run.
"He saw my advertising poster, and we finished at the same time across the line, which is awesome. And he was a good man.
"Those Scandinavians are tough, good genes."
Going around the same track 250 times could have been boring, but he became numb to it.
"I just had a really nice sunset, to be fair and a beautiful night.
"There was ... a bit of breeze. It wasn't too cold. And the moon was out."
After starting at 1pm on Saturday, he finished at 4.58am yesterday.
At the finish line he admitted getting a bit teary and emotional, surrounded by family and friends.
Yesterday he was feeling understandably spent.
"I'm literally, in bed. I can't even walk. I've got bruised feet, bruised toenails, everything's so sore.
"I had to get the parents to lift me up out of bed earlier."
His feat helped to raise $5000 towards mental health support for young males, with more set to come.
