The Ngati Pikiao descendant is currently in training to do a solo run from Bluff to Picton to raise awareness of the Ronald McDonald House.
Milne will run a total distance of 922km, literally running the equivalent of two marathons a day for 12 consecutive days.
The event is what Milne calls a practice run for next year where he plans to do a 1300km run around Tasmania.
Born in Rotorua, Milne - who owns the gym Kiwi Conditioning on Auckland's North Shore - has come a long way from being a penny diver at the Whakarewarewa Village in Rotorua.
"My best memory has to be Whaka and penny diving and just growing up around the village.
"I lived in Fenton Park but kicked around in the village everyday as a young fulla, and in the forest among the Redwoods."
He said those times were among his fondest memories - "just beautiful memories of my time growing up".
The father of one says his schooling consisted of Te Kura o Te Whakarewarewa, then Western Heights High School, before a stint with the New Zealand Navy.
Back then his upbringing was active, but not entirely sports orientated, Milne said.
"When I was growing up, I was active ... I went into the navy quite young. I started amateur boxing when I was about 14, with Michael Sykes and his young fullas, and then followed that up in the navy."
Milne spent about six-and-a-half-years in the navy.
He left the service in 2002, giving up competitive boxing and all physical exercise. He went from a lean and fit 74kg to an unhealthy 116kg.
A jibe from his grandfather Bert gave Milne the impetus to get back into training.
"I came back from overseas and I was about 116kg. I'm a bit of a short fulla, so I was like a perfect circle ... We were having his 70th birthday and I was having a feed and sweating hard out.
"He [Bert] looked at me and said 'you look disgusting and you've only got yourself to blame.' He said this in front of the whole whanau and I was devastated," Milne said.
"The next morning, to cut a long story short, I was hung over and feeling sorry for myself, I went for a run and never looked back."
Milne's journey to a fitter and healthier lifestyle took him to Australia, where he became a personal trainer and studied sport psychology and got into crossfit training.
Crossfit is a strength and conditioning fitness programme which combines weightlifting, sprinting and gymnastics.
"I got into the crossfit scene which is quite a hot word at the moment in New Zealand and pretty much for the last four or five years, I've been into the crossfit scene."
Two years ago, Milne said, he set up his gym, Kiwi Conditioning, to help encourage people towards a healthier lifestyle.
His clientele list includes sports athletes such as Cameron, ultra-endurance runner Lisa Tamati, golfer Zoe Brake and many others.
But it's not just high-profile athletes who grace his gym. There are mums, dads and even grandparents.
"We're pretty open door [here] and anyone can come along and it really doesn't matter if you're a mother of half a dozen kids or a first division rugby player.
"It's a real welcoming environment, we've got a good kaupapa here and a good community, it's awesome."
Milne said Cameron's fight tonight in Australia was exciting.
"I have no doubt in my mind that he will take away the win. He's ... really humble ... he's a people person and his work ethic is massive. He deserves to win," Milne said.
" I haven't had anything to do with his boxing ... He has his own coach for that, Henry Schuster, but ... he is crossfit. "
If Cameron wins it will be only the second time a New Zealand-born boxer has won a world boxing championship, since Billy Murphy knocked out Ike Weir in 1890.
New Zealand has had three residential world champs: Bob Fitzsimmons, who won the first of his three titles in 1891, was born in Cornwall, England; Mascelino Masoe, who won the WBA middleweight title in 2004, was born in Samoa and Daniella Smith, who won the women's IBF welterweight title in 2010, was born in England.
