Shuker and Stuart, who have both just turned 20, describe themselves as casual golfers who joined the Dannevirke Golf Club six months ago and play off a 34 handicap.
Shuker reckons it will take them 12 to 13 hours to complete the challenge.
"We'll be teeing off at 5.30am."
Shuker said the golf club had been helpful and members will have everything ready for their early start and will ensure they will be able to play through without any hold ups.
Neither Shuker nor Stuart have taken part in a Cancer Society fundraiser before.
"We saw an ad for the Longest Day challenge and as both of us have grandparents who had cancer we decided to give it a go," Shuker said.
They are joining hundreds of other New Zealanders who want to make a difference to the lives of people with cancer.
According to the Cancer Society every day 63 New Zealanders are diagnosed with cancer.
Already Shuker and Stuart have raised $1300 which has been donated by family, friends and workmates.
"Every donation we receive will go towards cancer research, prevention and support services for people who need our support the most."
Donations can be made to https://www.longestday.org.nz/krittaandcaleb