Dr Henry McLaughlin believes that physical and mental wellbeing can be improved by a daily mountain climb.
The idea is that people climb to the top of Slievemartin outside Rostrevor - known locally as the Cairn - take a selfie and then post the picture on the 'Cairnuary' Facebook page.
The mountain is 485m high, so Dr McLaughlin said if you climb it 31 times in a month, you've climbed higher than Everest.
He said he could see how his patients have benefitted.
"January's a time when I see a lot of depression and this challenge is pretty good for mental health and physical health," Dr McLaughlin said.
"A lot of people buy exercise bikes and then they gather dust. So this is something that's free, they get to climb up the mountain every day for a month.
"It's a  good hard exercise, it takes them about an hour.
"They don't need exercise bikes and they don't need to join gyms and pay money for stuff, it's out there and they can discover the mountains."
Those climbing the mountain can chose their own route - which could involve anything up to a 10km hike - or they can use a bike if they want.
Dr McLaughlin said between 30 to 50 people were now climbing the mountain daily and all sorts of people are taking part.
"There's one lady who's a patient of mine who's been very ill in the past and has had surgeries to her feet and really shouldn't be able to do it, but she's going from the car park half way up the mountain and she's doing it every day," he said.
"There's people with depression doing it - I know it's good for them - people who are overweight doing it, there are people who are very healthy doing it as well.
"People are all very encouraging of each other."
Dr McLaughlin said he climbed the mountain at about 06:00 GMT on Thursday and had eight other people for company.
"Normally you'd climb the mountain at six o'clock in the morning and you wouldn't see a soul," he said.
The final climb will be a communal one on Sunday, but Dr McLaughlin said he hoped to come up with something else to keep his patients exercising.
"I'm hoping to follow it on with some sort of challenge for the rest of the year that will keep them doing stuff," he said.
"As far as I'm concerned, it's probably doing my work good in that maybe some people are going to get fit that I won't see.
"I'd recommend it to anybody. There could be a cairn near you, it doesn't have to be my cairn, it could be a hill or a mountain near you."
A County Down GP has come up with a novel, if strenuous, way to get healthy and beat the January blues.