This motivation will help him swim 2km, bike 90km, and walk/run another 21km. His goal is to beat last year's time - "I'd be happy with eight hours."
He tells the story of his first triathlon with workmates, who asked him which part of the race he would like to compete in. Swim, run, or cycle? To the shock of his team, and without any experience, he chose the swim, declaring: "Well, I've got three months to learn!"
His confidence to swim has now grown to the point of his Ironmaori training consisting of swimming the whole 2km at Pandora Pond before a training cycle.
It is this extending of the comfort zone he is passing on by example to his students at Puawaitanga Academy.
In its fourth year, the academy encourages 13-24-year-olds to participate in sports to stay active and healthy. This year five teams from the academy will compete in Ironmaori, with each team member competing in a separate part of the race. But entry came with the rule they had to choose a different code from the previous year. This is because repeating a code would "defeat the purpose, because you're automatically going back into your comfort zone," he says.
In their fourth year, Tamati expects each of them to do the whole race.
The name Puawaitanga, he said, roughly translates to the blossoming of a flower, meaning "it is our youth being able to excel".
Event organiser Heather Skipworth said the respect Tamati's peers held him in was massive.
"He's had a huge impact, not just with adults but with the young ones. I think it's because he's been a positive role model, and I think he has earned it."