Despite the many charitable causes Dunajtschik has championed over the years, including financing the helicopter rescue service now known as the Life Flight Trust, it was his latest gesture that was too big to let him keep slipping beneath the radar.
Health Minister Jonathan Coleman this week described his commitment as "extraordinary" and "unparalleled".
So Dunajtschik felt he had no choice but to allow his warm and cheerful nature to be shown to the country through numerous media interviews.
Dunajtschik was born in the former Yugoslavia in 1935, but is of German ethnicity, something which weighed in his favour when German troops occupied the country in 1941.
However, things changed after German forces retreated from Yugoslavia in 1944.
Dunajtschik was imprisoned by Yugoslav forces in a concentration camp at Knicanin, along the Danube River, together with thousands of other ethnically-German Yugoslavs.
Many died of starvation or disease, including Dunajtschik's grandmother.
"That's where I spent over three years," he says. "Eventually I escaped with my mother and ... as refugees we moved at night; through Yugoslavia, then Hungary and Austria and eventually ended up in the Black Forest in Germany."
Asked about his time in the camp, he says there wouldn't be space in this article to describe it.
"Let's put it this way. When you see today the suffering of refugees in the world, that was exactly what happened then. That is simply a fact of life when countries are at war and one wins and one loses."
Dunajtschik arrived in Germany around 1950, with very little education and in a country rebuilding from the war.
He managed to find an apprenticeship as a toolmaker, and during his training lived in a home for disabled people. That, plus his wartime experiences, has made him think of those less fortunate than himself.
"There I learned to appreciate how lucky I was to have a healthy body and mind and the others which didn't. Because I was given the opportunity to live in that home, which was founded by an industrialist in the 1880s, now that I am in a position that I can also do something, naturally I want to do it," he says.
After completing his training in 1954, he spent about five years travelling the world, looking for somewhere he could apply his new skills while also indulging his passion for the outdoors.
New Zealand fit those criteria and he settled here in the late 1950s.
"It was a lot quieter than it is now but that was what appealed to me," he says.
He quickly found work for a company, but after only a few months on Kiwi soil decided to establish a tool-making business of his own - Precision Grinders, which still operates in Wellington as PG 2000.
"The business was very lucrative for about 25 years and then in '87 I decided to retire and sold out to my nephew," he says.
Yet he was still relatively young, so decided to dabble in the property market, his first investment being through Sir Bob Jones.
"I took up property investment and development more or less as a hobby and I'm still in it," he says.
He started accumulating and adding value to commercial and residential property around central Wellington, realising he had the nous for the business.
"I could tell that with the passage of time the value of properties go up. I am absolutely convinced that time is the hardest worker for property investment," he says.
"In fact, quite some time ago Bob Jones said that ... all property developers go broke and the only exception he knows is that bugger Mark Dunajtschik and the reason he doesn't go broke is because he keeps his property."
His background aside, Dunajtschik has a few other characteristics that distinguish him from your typical property developer or investor - his lack of staff being just one.
"I only operate buildings in Wellington between the Basin Reserve and the railway station. The reason for that is I maintain and run the buildings myself and if they are in a concentrated area it's easier to move from one building to the other," he says.
Dunajtschik gets involved personally in everything from electrical, plumbing and carpentry work, to ensuring lifts and doors are working properly, to negotiating with potential tenants and agents.
He won't disclose how successful his property venture has been, but his minimalist approach has paid off.
When the chairman of the Wellington Hospital Foundation, Bill Day, asked if he was willing to contribute to a new children's hospital, Dunajtschik thought his background and experience could allow him to do more than that.
"After a conversation between my business partner and my life partner we decided, why not build it? Because, by utilising my expertise as a developer we would be able to produce more real estate than if we were to just write out a cheque and leave the bureaucrats to build it."
That's when he made the offer to fund and arrange to build the entire hospital.
Dunajtschik, who does not have any children himself, hastens to add that the Capital & Coast District Health Board will design the building and specify exactly what would be required of it.
Dunajtschik and the DHB are still going through the resource and building consent process, but he hopes to start turning soil early next year, with the construction process expected to take about 18 months.
Meanwhile, the 82-year-old's adventures continue as he prepares for another skiing trip to South America.
"Certain things I can't do as well as I used to but I still very actively have two skiing seasons a year. In a few weeks' time I go to Chile and in our summertime I go to the Northern Hemisphere: I go and Ski in Utah, California and Colorado and the likes," he says.
"Deer stalking has been my hobby all my life and I still do that. I used to play tennis a lot but I've got artificial knees now and they don't allow me to play tennis."
Dunajtschik is emphatic that he would not be in the position he is in today, nor would he be able to fund and build a hospital, without his partner of nearly half a century.
Dorothy Spotswood was reluctant to say too much to the media and wants to make it clear that neither she nor Dunajtschik are seeking any praise or publicity.
The 79-year-old, who is from New Zealand, says she continues to do all the books for Dunajtschik, but when asked if she was due some credit for getting the children's hospital built, she just said "no" - nine times.
"[Mark's] the man that works hard and all that ... I'm just behind the scenes," she says.
"He is just a person that likes to create and at night-time feel he's done a day's work. He will never stop working, that's for sure, simply because if he can do it, he will do it."
Mark Dunajtschik
Age: 82
Born: Pancevo, Yugoslavia, now part of Serbia
Lives: Oriental Bay, Wellington
Job: Property developer and investor
Qualifications: Tool maker apprenticeship, completed in 1954
Family: Life-partner Dorothy Spotswood
Last book read: Dunajtschik says he doesn't read many books these days, preferring trade and informational magazines
Last film watched: "I don't really watch films either. I work and I like sports." (He doesn't watch sports, he plays them).
