What started out as a simple run on the first day of his young daughter's cancer treatment has quickly evolved into something extraordinary.
Now Mikey Neville has just completed his 187th straight Olympic-length triathlon on behalf of daughter Snowy, five, who is undergoing treatment for an extremely rare form of childhood cancer.
Chichester College teacher Mikey, 39, is on course for 200 straight days of completing a 10k run, a 40k bike ride and a 1.5km length swim and his campaign, #Trieveryday4snowy has been backed by the Bosham community where the family live and so far raised £26,000 for charity.
Mikey said: "Seven months ago we were just a normal family enjoying the chaos that comes with having two young kids.
"But when Snowy was diagnosed with cancer our life was shattered into a million incomprehensible pieces.
"I will never forget the moment we were told our little girl had cancer. I will never forget having to tell grandparents, uncle and aunts, friends."
Snowy, who turned five last week, was diagnosed with Rhabdomyosarcoma, an extremely uncommon childhood cancer which affects only four in every one million children.
It was looking at a picture of Snowy before her first day at Bosham Primary School that alerted Mikey and wife Polly that something might be wrong.
Mikey said: "Almost as we took the picture we looked at it and noticed this swelling above one of her eyes.
"At first we thought we hadn't washed off face paint from a couple of days before properly."
'The rate of growth of the lump was scary', Mikey said, during the week between an immediate GP appointment and a referral to the oncology unit at Southampton General Hospital.
There a tumour the size of a large marble which had drooped over her eye was immediately removed, and after ten days which were the 'worst wait of our lives', the bombshell news of her cancer was delivered and Snowy began a sixth-month course of chemotherapy.
Halfway through the family was told she needed proton beam radiotherapy in America and they have recently returned from a two-month stay at University of Florida Health Proton Beam Institute, Jacksonville, where Snowy underwent 20 doses of treatment.
"Snowy has just been so brave, she's totally inspired us by the way all kinds of treatment has not got her down," proud dad Mikey said.
"The first couple of weeks after she lost her hair she loved ripping her hat off and surprising people.
"She does suffer but her spirit is incredibly strong and positive and her little sister Posy, despite being only two, has been incredibly in-tune. We can take her into hospital knowing it's a sure way of instantly picking Snowy up."
He said: "Both my wife and I are positive people and we have made sure everyone stays positive around Snowy, but it has been the biggest challenge of our lives.
"It's completely changed our lives but I think the campaign has given us something to really focus on."
Far from going in alone, friends, neighbours, teacher colleagues and children at Bosham Primary School, where Polly teaches, have been organising their own outdoor challenges.
Snowy's godfather George Storton has been organising his own Wacky Races, where up to 100 people of all ages have come together on wheels around the village, while five ladies raised £3,000 with their own triathlon.
"Snowy's treatment is nearly finished and at last we can see some light at the end of the tunnel," Mikey said.
"But even though my 200-tris is nearly finished this is something I know will continue.
"We feel blessed with the support we've had from all our family and friends helping us get through it but there's other families in similar situations and we hope they can benefit from this money.
"But it's also been about getting the message out there that exercise is such a great way of getting through tough times.
"In a selfish way this has helped me get through each day and stay strong and positive.
"There's been people who have never exercised in their lives suddenly say they're loving running and that's been one of the most inspiring things about this campaign."
So far just over £26,000 has been raised for three charities: The Sussex Snowdrop Trust and CLIC Sargent which have both supported the family, and Sarcoma UK, the national charity for sarcoma, an incredibly uncommon form of cancer which affects the bones and soft tissue.
A big day of outdoor activities is planned in Bosham to mark Mikey's 200th and final triathlon on Saturday, April 21, all welcome.
Read more about Snowy and the family's story and find out how you can get involved at https://trieveryday4snowy.com/