The group of 33, who call themselves the "Heavybreathers", are raising money for MSFT Productions, whose goal is to raise awareness about men’s mental health by sparking chats between men and their friends.
They are running 42km in the Emerson’s Dunedin marathon, on September 10.
The group’s Givealittle page has already raised more than $50,000.
Their efforts to get more men talking about mental health took on extra significance after member George Murray recently lost his brother to suicide.
Mr Murray said he did not expect the issue to hit so close to home.
"He was just an ordinary bloke with lots of friends," Mr Murray said.
Men needed to open up about their struggles, he said.
"We’ve got this stereotype of just holding it in.
Fellow Heavybreather Will Saunders said New Zealanders at times felt like they did not want to burden others with their problems.
Mr Saunders said part of why they started fundraising was about how people perceived young New Zealand men.
"They think a lot of the time we’re just breathers out on the piss, but this actually affects us and it has affected us, and we care about each other a lot," Mr Saunders said.
The Heavybreathers started training about 10 weeks ago and have collectively run 3600km, and show no signs of slowing down.
Heavybreather Josh Platt said their efforts showed what a group of men encouraging one another could achieve.
"No-one has done a marathon in this group, and no-one has ever really been a runner, but all of a sudden we’re all now all marathon-level fit and almost ready to go for the big day.
"That comes from everybody getting behind each other," Mr Platt said.
Where to get help:
Need to talk? Free call or text 1737 any time for support from a trained counsellor
Lifeline – 0800 543 354 (0800 LIFELINE) or free text 4357 (HELP)
Youthline – 0800 376 633, free text 234 or email talk@youthline.co.nz or online chat
Samaritans – 0800 726 666
Suicide Crisis Helpline – 0508 828 865 (0508 TAUTOKO)
Healthline – 0800 611 116
All services listed are available 24/7.
If it’s an emergency and you feel like you or someone else is at risk, call 111.
