The Edge Breakfast host Dom Harvey has pledged to run five marathons over five consecutive days to help raise funds for three-year-old Ka'iulani Forbes' cancer treatment.
Dom, Meg and Randell from The Edge met Ka'iulani on Friday, who suffers from a rare form of cancer called Neuroblastoma.
The disease will not respond to chemotherapy, and none of Ka'iulani's treatment is covered in New Zealand.
Her parents Moana and Manihira Forbes are urgently trying to raise the more than $260,000 necessary to access lifesaving treatment in Barcelona. They've even sold their house.
"This will make her better, it would eradicate her disease," Moana told the radio hosts.
On Monday, Dom announced he had a fundraising idea to try and help, appearing to fight back some emotion as explained the concept.
"I don't even know if this would be possible, but I'd certainly be prepared to give it a go," he said.
"What about five marathons in five days?"
Dom often runs marathons in his spare time, having written a book on the subject called Running: A Love Story.
Still, the broadcaster has never attempted 210km over five consecutive days.
"You're willing to put your body and mind through that?" asked co-host Meg.
"42km a day? You're willing to even try?"
"It's nothing compared to the pain this poor little toddler is going through right now," Dom replied.
Donations can be made to Ka'iulani's Givealittle page.