Hugh McLaughlin has taken to a treadmill in town centre where he's aiming to run the equivalent of a marathon a day for nearly a month.
He's over a week into the challenge and still has quite a distance to go.
"It's 759.8 miles which is Belfast to Paris," he explained.
Running 26 miles per day for 29 days may sound like a harebrained scheme, but Hugh will be raising money for cancer research with every step he takes.
We're coming for you, cancer!
He added: "My daddy had bladder cancer and they treated it and cured him and you're only going to get these kind of results by giving money and one day we'll beat cancer."
For 28 days Hugh will be running on a treadmill in the town centre.
He needs to eat 3,000 calories per day to keep going, but he's also being fuelled by the food and support given by locals.
On the 29th day he'll finish his challenge by running the Belfast marathon.
Hugh's wife Tracy says she's confident he can make it.
She said: "He is very dedicated and when he does something like this he puts everything into it and I've every faith in him he'll complete it."