Years of protesting against social injustices was followed by a fascinating career straddling two seemingly disparate worlds: investment banking and philanthropy.
After years as a lawyer specialising in international finance, where she'd wring millions from complex deals, she took the top job at the Bermuda Commercial Bank, where she stayed for 4 years.
But her biggest achievement is the revolutionary organisation she started in 1998.
Adara Group (originally called the Isis Foundation but renamed for obvious reasons), is a corporate advisory business set up to fund and provide services to help people living in poverty.
It's an innovative concept that Exel says gets around the challenge that all non-profits face: they're so busy raising money they can't focus on helping people.
Working with community groups, Adara Development funds and manages health, education and essential services projects for women and children in remote areas of Nepal and Uganda.
It's a small company with just 200 on the payroll but they touch the lives of 50,000 year people each year. Adara is now considered a global leader in delivering medical care to neo-natal babies in low resource settings, having set up intensive care and maternity units in Uganda.
They've also acquired a wealth of data and research on maternal and child health, and worked with at-risk children, rescuing many from a life of trafficking.
The work itself can be enormously emotional, says Exel, but it's matched by the huge sense of pride it gives her.
So how did a girl from Waikanae end up in such a position?
A self-described "loudmouth", she was on the debating team at school and figured she'd end up working as a human rights lawyer for the United Nations, or as an advocate.
"I was an independent thinker," she says. "I don't remember leading the Girls Guides, but I was always determined to discover my own path."
After studying arts and law in Wellington, she went to Australia to compete at the National Parachute Championships, after getting hooked on skydiving.
But after hurting her knee in an accident, she ended up staying in Melbourne to finish her law degree.
Several of the students there were clearly wealthy, and Exel realised there was a "world of money and power I didn't know about or understand", and that if she wanted to affect change, she'd need to.
She went to work for the most business-orientated law firm she could find, imagining she'd be a spy in the enemy camp.
"I had to confront my prejudices, because a lot of these people have great values and integrity. A scarier realisation was that I really enjoyed business and a deal."
Much to the amusement of her family, the young woman who'd spent plenty of time at protest rallies continued her climb up the corporate ladder, specialising in mergers and acquisitions in Sydney and Hong Kong, in the days when big companies moved assets to Bermuda.
After a couple of years of travel, she moved there to lead the Bermuda Commercial Bank, becoming the youngest woman in the world to lead a publicly-traded bank. It was a complex role that was "terrifying in every way".
"I often say to young people, when a door opens, no matter how afraid you are, throw yourself through it. It was challenging in so many ways but amazing. I could not have paid to learn what I got the chance to.
"It taught me that great leadership is about unlocking skills in people. Because my team knew way more than I did about banking."
In 1995, she was elected a Global Leader for Tomorrow by The World Economic Forum.
They might have known an even bigger challenge was to come, one that would draw on her passion for social justice, and combine it with her business skills. Exel credits her youthful energy, enthusiasm and naivety as the push she needed to start Adara, thinking, "go big or go home".
She'd trekked in Nepal and had met the First Lady of Uganda while running the bank, so it was a personal connection that focused her attention on those regions. "My particular bugbear in human rights is remote service delivery. There's an economic argument that you get more bang for your buck in an urban setting. I understand that but if you live remotely in poverty, the NGOs won't come near you. If you're in a landlocked country it's worse."
Exel says she might never have made the leap at all had she known what was around the corner: Ebola outbreaks, the civil war in Nepal, September 11, the global financial crisis, the huge complexity involved in merging a business with a non-profit, the massive responsibility of caring for vulnerable people.
"It's like playing with a loaded gun," she says.
"If you're intervening in someone's life when they're really vulnerable it's an incredibly serious thing.
"People would say it was visionary. I say I didn't know what I was doing. One thing I've discovered about entrepreneurs is they often do things without fully realising the consequences, which allows you to be more creative. It comes down to how you think about risk. It's true, I've lived with lot of risk and I'm comfortable living with risk."
But it's a risk that has paid off. She's never been more proud as when she joined the Adara team in the aftermath of the catastrophic Nepal earthquake. Finding the right team was a crucial part of the journey, she adds, heaping praise on those who have stood by her since the beginning, and the leaders within the communities she's worked with on the ground.
In 2013, Exel was awarded an honorary Order of Australia for service to humanity and was recognised by Forbes as a "Hero of Philanthropy" in 2014.
If there's one message she hopes impart, it's that philanthropy doesn't just have to happen at the end of a career but can be integrated throughout. "You don't have be a great leader, you just have to be filled with passion, be authentic and give it your best. Then you can make change."
