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Matheson Brown, 28, from New Plymouth has just smashed a world record, becoming the fastest person to climb the highest peak in every US state.
The clock started at Denali in Alaska and did not stop until he got to Mount Rainier in Washington.
The epic feat was achieved in just 20 days, 14 hours and four minutes with the help of his dad and two friends, no second was wasted.
They climbed at all hours of the day and night, sleeping for as little as an hour at the time. But it wasn't all about the glory of holding a title.
Brown wanted to prove that regular people can achieve big things, even without major resources or professional backing.
The first thing he had to work out was the logistics, he told RNZ's Nine to Noon, and logistics on a budget - the previous record holder had a private jet to ferry him between peaks, he says.
"We had a big piece of cardboard, we drew a map of the US on it, and then drew where all the high points were, and went on Google Maps and drew lines everywhere linking up all the states.
"And then the game was try and link up all the red dots which were the high points and have the smallest score possible, the score being the number of days it takes to drive between them."
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The shape of the US proved a challenge, he says.
"Maine is tucked way up into Canada on the top right-hand corner, if you're looking at a map. And so, once you get there, unless you're flying, you either have to finish there or do a huge amount doubling back on where you've just driven.
"So, the key was trying to link up all the states with there being the smallest amount of wasted distance."
Unfortunately, there was no way to make the plan work finishing up there in Maine, he said.
"So, we did have to do that huge double-back drive, which I was like avoiding from the start. We ended up losing a lot of time there."
Unlike the previous record-holder, he couldn't make up time flying between peaks, he said.
"You can't really make up time from the driving, you're already doing the speed limit.
"The only place to make up time was with the climbing. So that's what we did. We basically were running, so many of them we ran."
When you're running up mountains, and driving constantly to reach them, fatigue is inevitable, he said.
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"I don't think I ever slept for more than an hour at a time. And I don't think I ever slept for more four hours on any day."
There were periods, he said, when he couldn't tell if his eyes were open or closed.
"That's not that bad, but if you keep pushing that for another 45 minutes to an hour, eventually your head will start to just drop towards the ground, and you sort of catch yourself mid fall.
"You're literally falling asleep while you're walking, and you're hallucinating and all that."
Each peak presented its own unique challenges, he said.
"It's pretty varied. Sometimes it's fine, and when it's really nice conditions, you're like, oh, man, this is actually kind of easy.
"I'll ski this and then you come back on a different day, and it's like bulletproof Alpine ice, and you can barely walk on it with crampons, like the teeth won't bite in because it's so, so cold and hard. We got a little bit of everything."
Brown funded the whole enterprise himself, including the cost of two months of training in Colorado before he took the record on.
"I just had some points to wanted to prove, and I managed to prove it. I wanted to show that people could go for the things that they wanted to go for, and they don't have to have all the sponsors and stuff like that."
Having said that, for his next adventure, sponsors were welcome, he said.
"You can still work a 12-hour day and go and train afterwards, you can do that seven days a week, but you won't be as good as you would be if you were able to train more often.
"So now I definitely am open to sponsors."
