His keen sense of determination showed early just before we set off around the base track, with one of Marsh's sons wishing him luck.
"I don't need luck," Marsh replied. "I've got the Lord."
Marsh's strong Christian faith has been with him since he dedicated his life to God at 12 year of age when he made a commitment to serve as a missionary. He later served with Hazel in Papua New Guinea's Sandaun Province for 13 years.
Our group set off from the Pilot Bay side of the base track at 10.30am - 13 family members of all generations keeping Marsh company.
His three sons - Lew, John and Tim - all joined him for the walk, with their wives Sharman, Bev and Sue, along with several of Marsh's grandchildren and great-grandchildren.
Marsh set the pace, and when passers-by watched us in our column, daughter-in-law Sharman explained the reason for our walk.
While Marsh was a printer by trade for most of his working life, he's no stranger to the outdoors, having served in World War II, and lived on an outback bush station during his time in Papua New Guinea.
In his 80s, Marsh began training for the Rotorua Fletcher Marathon, which he completed six times over seven years.
His final marathon took place just a couple of weeks before his 89th birthday.
He has always been an outdoorsman and has encouraged his sons to be as well, eldest son Lew recalled.
"As kids, we used to wander down the creek and play there all day in the holidays," he said.
"When he was about 52, he went off to Papua New Guinea ... a lot of his life has been spent outdoors."
At the end of the walk, about two hours after we set off, Marsh is slightly breathless but bright-eyed.
He's proud he made it around Mauao without help - especially considering he has glaucoma in one eye.
"There are times when you need help, but there are times when you do better on your own, I think," he said.