Wanting something a little more serious he went into the New Zealand Army full time.
When a student he joined the part-time Territorial Force and commissioned into the Royal New Zealand Armoured Core, based at an armoured reconnaissance unit in Napier.
Being a soldier wasn't a vocation at first.
"I didn't have a particular plan. I was walking across the quad, as one does at university, and a friend of mine asked me what I was doing. I said I was going for a coffee.
"I asked what he was doing and he said he was going to join the Army and why don't I come along.
"So I said sure, why not - there is nothing else to do. He lasted for three years and I have lasted for 33 years - I'm still in as a regimental colonel of an infantry battalion."
After two years he shopped his CV around corporations and was picked up by multinational Fletcher Challenge, one of the country's largest companies with interests in construction, forestry, building and energy, initially within New Zealand and then internationally.
He quickly rose through the ranks in HR and was running a Fletcher Wood Panels manufacturing plant when shoulder-tapped by Skellerup Group, with a view to becoming chief executive of the distribution division.
"That never happened because it collapsed."
Skellerup reincarnated as Viking Pacific and became "probably New Zealand's largest leveraged-debt environment", funded by Goldman Sachs' United States office.
"I wanted to be in business for myself and I set up Hunter Powell Investments and have never looked back."
Formed in 1999 he holds an equal shareholding with wife Sharon Hunter, a former owner of PC Direct.
"Hunter Powell Investments is the investment vehicle we use to buy businesses and so forth but we don't do anything together. Other than sharing Hunter Powell we try to keep things quite separate - there has to be a division between married and business life or else you are living and breathing a 24-hour experience, but we are hugely supportive of each other."
The new company wasted no time, investing in Continental Distributors, relaunched as Euro Pacific Foods.
Through government contracts including the armed forces, turnover doubled.
"At the time no one company could really supply everything in the right way. We got together with people we would normally consider competitors and collaborated in a joint proposal to government to supply a range of things in a very innovative way using technology. It was called EDI in those days - Electronic Data Interface - which took things to a whole new level of customer service they had not experienced."
Remaining in the Territorial Force with rank of major, in 2001 he became a United Nations peacekeeper in Lebanon, bringing his family with him.
The former human resources manager still had a lot to learn.
"As deputy chief of the unit I was responsible for whole lot of different officers and soldiers from 22 separate nations with very diverse cultures.
"The difference in operating standards and ability to get on with each other was a profound wake-up. I had done business internationally but normally you are dealing with one group in one country at one time. It was very interesting to get people to do a patrol cycle, where people from different nationalities will simply not be in the same vehicle together - they can't be. That was interesting to learn.
His family lived in Israel, where his son learned to ride a bike and his daughter to walk.
"In the end it became untenable - it was becoming ridiculously unsafe. They were evacuated along with other nations and I stayed on to finish my second tour."
A "huge fascination" remains for the Middle East.
"We were there in the days of the investigation into Iraq's weapons of mass destruction and the deployment of inspectors. Since then there has been the most extraordinary amount of activity with Iraq and Afghanistan and now what is happening in Syria. It is very sad to see the way it has unfolded.
"I have deep sadness on what the world has currently become."
His entrepreneurial spark remained and he partnered with special forces officers to form maritime Security business Envoy 360, headquartered in Dubai.
"We had contracts all over that part of the world and we were protecting ships in some very high-risk zones such as the Gulf of Aden, which runs past Somalia and remains a very tricky area today.
"I said to the guys when we get to land-based security operations, which was inevitable, I want out.
"We won a very large contract with [Texas oil company] Anadarko, jointly based in Mozambique and Kenya. At that stage Hunter Powell exited."
Home success
Back in New Zealand Euro Pacific Foods was sold to form the New Zealand Rental Group, a partnership with Goldman Sachs JB Were to purchase Hirepool, which was turned into a successful national equipment-rental business.
"We took Hirepool national in 36 months because I believed we needed to maintain momentum for a roll-up and roll-out strategy.
"Buying businesses/opening greenfield branches requires a pace that, in my view, can't be interrupted. The last thing you want is to be bogged down halfway by competitor activity."
The competition never arrived and a national footprint established. Its number one competitor, Hirequip, went into receivership and is now owned by Hirepool.
He said Hirepool's pre-existing "DNA" made the establishment of a national chain easier.
"We had a very strong internal culture that was super high morale, and dedicated to have very high standards of service.
"It's the old adage of high staff morale equals great customer service, equals cash flow."
He stepped down from his CEO role with Hirepool owner New Zealand Rental Group after growing Hirepool from 14 branches to 86.
Some branches were more favoured than others.
"It was a great joy to have a reason to go back to Wairoa."
Hunter Powell became a cornerstone investor in Greenlane Biogas Technologies in 2013, with Mr Powell as CEO. It is the leading global developer and supplier of technology for upgrading biogas to readily-utilised biomethane.
With the business streamlined and a China joint venture signed, he sold it for eight times its purchase price to a listed UK company the following year.
While he is a captain of industry with a unique insight into global hotspots, he has a bee in his bonnet over developing small businesses. He convenes the government's Small Business Development Group.
"Our small-business economy is critically important to New Zealand. It represents 97 per cent of businesses, employs 30 per cent of all employees and produces 29 per cent of GDP output.
"Tourism is one example - the vast majority of tourist operators are SMEs and that is a multibillion-dollar business for New Zealand.
"Small business is a critically important sector that, as a country, we are only beginning to realise the importance of. Not just economically but socio-economically - employment within it is forever growing."
It was ironic small business was far more demanding than corporate business, he said.
Small-business owners are usually a general manager from day one. They do everything from marketing to finance to logistics to HR. In larger companies key functions are disseminated to so-called professional specialists.
"That diversity can be wonderful for some people and very challenging to others. I have the ability to talk, I guess, about the challenges with that. When I look at the members of the Small Business Development Group each and every one of them brings a special capability to the party which is why we have the ability to talk to very senior government officials across a range of departments."
Innovation
The Group successfully lobbied for what is the biggest tax shakeup for small-to-medium businesses in decades, announced in this year's Budget. Small businesses will be able to pay provisional tax using their accounting software, a pay-as-you-go change from forward estimates and advance payments.
Small Business Minister Craig Foss said provisional tax and was one of the main complaints from small- to medium-sized companies.
New systems would remove anxiety and save many thousands of hours' toil "and let businesses get on and do what they do".
Mr Powell said New Zealand was a pioneering nation and its people keen to own their own businesses.
"We are in love with start-ups, and that's a good thing, but I'd like to see it more balanced with a similar view on scale-ups, like what we did with Hirepool - taking a small entity and making it big.
"There is an unprecedented opportunity arriving soon with ageing baby boomers wanting to exit their businesses.
"My particular view is there is going to be unprecedented sector consolidations which would be scale-ups by definition. "
He said New Zealand lacked "very deep capital markets" that invested in intellectual property, which was the motivation behind KiwiNet.
The Kiwi Innovation Network is a network of public research organisations, working together to develop scientific discoveries into marketable products and services.
Chaired by former Finance Minister Ruth Richardson it came from an Entrepreneurial Summit idea.
The Summit, co-chaired by Tenby Powell and Sharon Hunter soon after the Global Financial Crisis, was an attempted to spark enthusiasm back into the economy and foster a startup culture.
Other public roles in addition to his many private investment and management duties are: chairman of Waikato Link, the commercialisation and technology transfer company of the University of Waikato of which he is a distinguished alumni; chairman of Aldera, a New Zealand company dedicated to creating diversified solutions for the animal health industry; chairman designate of unIPartners, a proposed Australian public company focused on the creation of start-up companies from university research and member of the New Zealand Sector Workforce Engagement Programme, a government body to support businesses access to skilled staff.
He was appointed by the Minister of Defence to serve on the 2015/16 selection panel for the Navy, Army and Air Force chiefs.
He said there was not a wide appreciation in New Zealand for the wider value of the armed services.
"I learned some wonderful skills, not just physical confidence, but confidence in working with a range of people you would not otherwise necessarily be exposed to. The skillsets required are hard to replicate anywhere else. You are not just dealing with inclement weather and lack of food and lack of sleep. You learn a lot about yourself and an awful lot about working with others from all walks of life.
"We take young kids and train them to a very high level, not just as soldiers but as highly contributing members of society."