"After that there was a bit of a sojourn to art school in Dunedin and then an accountancy degree," she said.
"That was a dare from my father, who thought I should be a little more substantive in the way I was approaching my life."
She said she always had "an appetite to work".
"That's possibly because I've pursued things I'm highly interested in, so I don't really see work as 'work'."
The title for the book is inspired by the slow transition from new business owner to a successful one.
"You start off in a really gritty space, where it's about getting things profitable and employing people. It's all consuming," Stretton said.
"Initially, it's about survival. When you're in that mode it's fight or flight."
A big part of her current operation is the Stretton Foundation, which was set up in 2013.
The first charity to come out of it, RAW (Reclaim Another Woman), works towards breaking the cycle of intergenerational offending, educational underachievement, poverty and violence for disadvantaged women.
"If you're lucky enough be able to build a revenue stream you start to reflect on a bigger contribution," Stretton said.
"The women of RAW have taught me so much, and the big thing is that there are always two realities in play when you're interacting with another person.
"To develop that EQ [emotional intelligence] is really important, and a lot of people don't. It becomes all about their reality and what they need, rather than reflecting on the other reality that's sitting there as well."
The new book was about "drawing a line in the sand", Stretton said.
"Thirty years is significant, especially in the fashion industry. It's hard work.
"I'm fortunate to have my daughter as the succession plan for my label. It's been pretty powerful to have her willingly want to do that, it's not something she feels she has to."
Stretton still has strong connections to Whanganui.
At one stage she had 30 outlets across the country, including one here in town.
"That was great because I got to come back for visits and spend time there. It really is a beautiful city.
"My uncle James Carver, who recently passed, lived in Whanganui all his life. I've still got cousins and an aunt there.
"I actually saw a house on College St come up for sale in the Herald about a year ago, which was where my grandmother lived."
The H G Carver Memorial Library at Collegiate is named after Stretton's grandfather, George Carver, who was a housemaster and teacher at the school.
The "grace" part of her journey came a little bit later, she said.
"I often talk about failure being the foundation stone of my success.
"When the difficult stuff happens, it's the only time you get to stop, self reflect, and think 'Okay, how could I have done this differently?'
"Now that I'm much more into the 'grace space', you know how to work with and nurture people, and make sure the employment relationship is collaborative so you're both delivering equally."
Grit Before Grace can be pre-ordered online.
All profits from sales will help to fund the work of Hope Fish, another charity from the Stretton Foundation.
