Fisher ran his first half marathon in 2010 and his first full marathon last year. He ended the year taking on the 60km Kepler Challenge.
"I find that with each of those goals passed, I feel a great sense of achievement," he said. "The 100km ultra has been the ultimate goal."
Also taking part tomorrow will be 41-year-old Allan Wong Kam of Stonefields who, on his 40th birthday, set himself the goal of running 50 half marathons by the time he is 50. Tomorrow will be his 13th.
"I did the Taupo off-road half and I loved it and thought I needed a goal to keep me off the couch," he said.
"It is all about participating for me. I get friends asking me 'When are you going to do under two hours?' and I just ask them, 'When are you going to join me?' I have done 12 now and I am proud of that. I am ahead of schedule."
David Ching has signed up his family of five - his wife and children aged 12, 14 and 16 - for the family event in an attempt to get them into off-road sport.
"We love the outdoors and have always gone bush-walking as a family in the Waitakeres," said the 47-year-old, who is the director of sport at St Cuthberts College.
"We are a really active family -we all play hockey and the kids all play cricket. We've done a number of on-road runs over the year but getting into the bush is so much more beautiful and interesting."
Marcus Graham, who is originally from Hawkes Bay but has lived in Brisbane for the past eight years, is home for two weeks and is fitting in a few events while he is on holiday.
"Though my family and a few friends have suggested holidays should consist of relaxing - this is my perfect idea of a holiday," said the 32-year-old graphic designer, who will also compete in the Takapuna Cup outrigger race next week.
Graham knows very little about the Riverhead course, which will be his first competitive off-road event in New Zealand.
"I can't wait to get a bit muddy - that's probably what I'm looking forward to the most."
All the competitors share a bond of adventure and setting a goal and achieving it. It is the fourth year for the Trailfest event and the number of athletes competing has doubled since its inception.
About 60 per cent of the field will be runners and walkers, and 40 per cent will be bikers.
Event manager Cam Carter said the Trailfest was one of the most diverse events in total sport, as it had nine different options and distances.
"This event is excellent for people based in Auckland because you have a massive arrangement of quality trails so close to the city," Carter said.
"And with the number of options we have, it's really accessible to everyone. It's also one of those few spots that you can use for mountain biking."
Mountain biking, cycling and BMX are skyrocketing in popularity among New Zealanders.
A recent Sport and Recreation survey found almost one million Kiwi adults now class themselves as regular cyclists - nearly double the total of 10 years ago.
"Mountain biking provides a sustainable medium to be active and spend time in nature while also being in a social environment," said Carter.
"You can incorporate mountain biking into your daily life for transport, fun and fitness, so it's nice to foster this healthy lifestyle and culture."
The Xterra Trailfest Riverhead caters for athletes of all abilities.
There is a duathlon-style off-road event which is a 22km mountain bike followed by a 12km run.
This event has been designed to suit those training for the Xterra Rotorua event to be held in a couple of months.
For all involved in Riverhead, the Trailfest is a good adventure.
Riverhead Trailfest
When: Tomorrow
Where: Riverhead Forest, Ararimu Valley Rd, Auckland
Nine event options
Walk / run: 6km, 12km, 22km, 34km
MTB: 12km, 22km, 34km, 45km
Off-road duathlon: 22km MTB and 12km run
Entries are taken on event day.
