He excelled on Southland primary school cross country scene and aged "12 or 13" opted to pursue the sport more seriously.
First coached by Lorne Singer and he was immediately taken with the thrill of training in a more structured way.
"I really enjoyed training more seriously," says Jack. "I used to train by myself most days, but working with a coach helped focus on certain areas. I carried out different sessions and by mixing up my training, it made it more interesting."
After a year with Singer in 2011 he switched to his current coach, Lance Smith, a man whom Jack describes as an "incredible mentor." The pair have worked well together with Smith empowering his protégé to problem solve and make his own coaching decisions where necessary.
The recipe has worked. The former Central Southland College student grabbed both the under-14 and under-15 Southland Cross Country titles and as a Year Nine student he snared a silver medal at the 2011 New Zealand Secondary Schools' Cross Country Championships in Ashburton.
On the track he later won 1500m and 3000m medals at the South Island Championships but only began mounting the top of the podium on a more regular basis once he switched to the steeplechase.
In 2014 Jack secured gold in the 2000m steeplechase at both the New Zealand Secondary Schools' Championships and New Zealand Track & Field Championships (in the men's youth event). Last year he banked the junior men's 3000m steeplechase title at New Zealand nationals.
"I didn't have a lot of success on the track until I started the chase," he explains. "The steeplechase is more of an endurance race which suits me," he explains.
A genuine all-round endurance talent, it was coach Smith who first suggested Jack should give the 2015 New Zealand Mountain Running Championships a crack. It proved a piece of inspired judgement as the hill-loving athlete romped to a victory in the junior men's race - in his mountain running debut - by more than a minute-and-a-half in Nelson's Grampian Hills.
"It went better than anticipated and it was probably my best race of 2015," explains Jack. "It just felt right to me. I have real endurance and I enjoy the changing gradient and terrain. It is a completely different type of running to the track and one in which I can excel."
Preparing to compete in the generally flat environment of Winton for last year's
World Mountain Running Championships in Wales was far from ideal. Yet despite this he produced an outstanding display on his international debut to place 12th where he excelled on the uphill stretches.
"I didn't really know what to expect and I would have been quite happy to finish in the top half of the field," he explains. "I was definitely a lot stronger on the uphills and at the top of the mountain I was in fourth place. I lost quite a few places on the downhill and slipped back to 20th only to regain place on the uphill again to finish 12th. I was really happy with my performance. It was a definite highlight of 2015."
Since then Jack has finished school at Central Southland College and relocated to Queenstown to live with his grandparents. Taking a gap year from his studies he works for between 30 to 40 hours per week at Pita Pit, but significantly he is exposed to a stunning training environment which offers the very finest of mountain running.
"I've been here for five months and it is a great place for me to train at with the endless hills to run on," says Jack, who cites the Ben Lomond Trail and Big Hill Trail as two of his favourites running routes.
"Running the trails has proved really good for my training and I'm now in the best shape I've ever been in," he adds.
Training around 100km a week and at least three times a week up in the mountains he has recently adjusted many of his reps to take place in the hills, including a gruelling 8x5min session, which he averages at a pace of four minutes per kilometre.
The regime appears to be working as he comfortably retained his junior title by a victory margin of more than three minutes in May's New Zealand Mountain Running Championships on the Ben Lomond track he knows so well. Yet his improved strength has also reaped rewards in all other disciplines as he ran a half-marathon PB 1:11:30 in appalling conditions to win the Gore Half-Marathon in May and earlier this year he has also posted PB's on the track this year in five events (1500m, mile, 3000 steeplechase, 5000m and 10,000m) the latter time of 33:05.51 earning him a bronze medal in the junior national championship for the 25-lap distance.
His next target is the World Mountain Running Championships in Bulgaria in September and with this year's race at Sapareva Banya a pure uphill event (the championship run uphill only and uphill/downhill races on alternate years) he believes he is more than capable of a strong showing in what will be his final stab at the junior race.
"It is my main race of the year," he explains of the race, which includes 1000m of elevation over a distance of around 8km. "My goal is to finish in the top three. From the start I will try and hang on to the leaders. I'd be happy with a top three."
Beyond Bulgaria the Southlander is still hopeful of making progress on the track, road and cross country as well as mountain running and one day has aspirations to make the Olympics.
But for now expect Jack to most likely to be seen running up a mountain and delighting in the experience.
"It is so much more enjoyable to me when I'm running the hills," he explains. "I don't notice time go by at all. For me running on the track compared to mountain running is like comparing running on a treadmill with running outside. For me running in the mountains gives me so much more freedom."
