He has climbed mountains, even Mt Everest, he has run marathons around the world, even on Antarctica, and he has skied at the Winter World Masters Games.
"I do it because the opportunity is there," says Gluckman, a retired dairy farmer fromMatakana. "Why not, someone has got to do it.
"I don't analyse these things. I just love the challenges and meeting people."
Modest, maybe, but Gluckman, now aged 66, is proud of his achievements. He has reached the summit of all the highest mountains in the seven continents and he has run a marathon in each continent.
He has completed the Shackleton Crossing expedition in Antarctica and, this May, plans to ski the ice caps of Iceland and scale its highest mountain, Hvannadalshnúkur (2100m).
A month before that, he will set his sights on the World Masters Games athletics in Auckland, competing in three events - the 800m and 1500m on the track, and the 10km road race in the 65-69 age category.
It is his fourth Summer World Masters Games, having competed at Melbourne in 2002, Sydney 2009 (reaching the 1500m final in the 55-59 age group) and in Turin, Italy 2013.
In 1997, John Gluckman took on Mt Everest and won.
"I'm not sure whether I will get a medal (in Auckland, but you never know," says Gluckman, younger brother of Sir Peter Gluckman, chief science advisor for the Prime Minister. "I will do my best.
"I never thought I would get a medal at the Winter World Masters Games and I never thought I would get up Mt Everest. Sometimes, the most unlikely people make it.
"After all the long-distance running, I found I had a mix of speed and endurance in the shorter distances. I never realised that in my younger days.
"The shorter ones don't tire me out as much, but I have to improve on my start - it's awful at the moment."
Gluckman travelled independently to his second Winter Games at Quebec City in February 2015 - he also attended Bled, Slovenia in 2010 - and won bronze in the 60-64 age group, combining with a Russian and two Frenchmen in the 4x5km cross-country ski relay.
"I felt like the Jamaican bobsleigh team in the Cool Runnings [movie]. I trained at the Snowplanet [in Silverdale] beforehand.
"I'd take my cross-country skiis, walk up the slope and ski down. I could get up twice as fast as the lift and I did that routine 41 times in an hour.
"I entered the relay [at Quebec] to make up the numbers, and I met the Russian and Frenchmen on the day. They didn't speak much English and I haven't had contact with them since."
Gluckman climbed Mt Everest in 1993 with a group of 10, taking five days to get to the summit and two days to return to the base camp.
"I really didn't think I would get up - I thought only the powerful, strong climbers get up.
"So I thought `Can an average guy do it?'. The climb was difficult, yes, but it wasn't nearly as impossible as I thought it would be.
"I was on the summit for 20 minutes and took a couple of photos - that was it. You don't see a great deal - just the Tibetan Plateau to the north, the foothills of the Himalayas and plains of India to the south, and the Himalayas to the east and west.
"I was a bit tired to appreciate it all and it never sunk in until two days later," he says.
He returned to Nepal in 1997 and ran the Everest Marathon, taking him eight hours, because of the altitude and rough trail.
"Ninety started and I finished in the middle of the field."
In 2002, Gluckman was experienced an "hostile" environment, running the Antarctica Marathon on the snow, ice and stones of King George Island in a time of 5h 20m.
"I'm not over-organised. If you become a slave to a training schedule, it doesn't always work."
Gluckman ran his 100-hectare dairy farm at Matakana for 33 years, until he sold it and his herd of 240 cows in June this year.
He kept one hectare and his house, and planned more adventures in his retirement, including taking in the World Masters Games in Kansai, Japan, in 2021.
"The way I see it, life is a journey, not a destination," he says. "I would like to keep running for another 10 years and if I can't run any more, then I will take up something else."
John Gluckman's Achievements Mountain climbing (Seven Summits) 1990 Mt Vinson 4897m, Antarctica 1992 Cartensz Pyramid 4884m, Indonesia New Guinea (Oceania) 1993 Mt Everest 8848m, Nepal (Asia) 1994 Mt McKinley, now named Denali 6194m, Alaska (North America) 1996 Mt Aconcagua 6961m, Argentina (South America) 1999 Mt Kilimanjaro 5895m, Tanzania (Africa) 2000 Mt Elbrus 5642m, Caucasus, Russia (Europe)
Marathon (Seven Continents) 1997 Everest Marathon, from near base camp to Namche Bazaar (Asia) 2002 The Last Marathon, King George Island, Antarctica, time 5h 20m 2003 (July), Gold Coast Marathon (Oceania), 3h 58m 2003 (November), Frankfurt (Europe) and New York (North America) Marathons, 4h 15m 2004 (March), Kilimanjaro Marathon (Africa), 5h 2004 (April), Santiago Marathon, Chile (South America), 4h 20m
