The same happy-go-lucky attitude that's seen her through 102 years makes it difficult for Ella Bayes to pinpoint exactly why she's lived so long.
"I don't know. I guess it's in the genes," the Whangarei woman said, at the first of two events planned to celebrate the milestone - a Thai lunch with her daughter Lynda Brown and friends yesterday.
A happy disposition, "not stressing" and plenty of exercise have certainly helped her to achieve the rare milestone tomorrow.
Ms Bayes lives in a self-contained apartment at Jane Mander Retirement Village and took part in the village's exercise club, likes needlework and loves plants and flowers.
"I'll have a go at anything, really ... And it's nice to be surrounded by family and friends," she said.
Ms Brown said to this day her mother refused to take an elevator, instead opting for the stairs as part of staying active.
"She'll be back, next year, too," Ms Brown, one of Ms Bayes' two children, said.
Other descendants included five grandchildren and eight great-grandchildren.
Ms Bayes spent her early years at Red Beach, leaving school to work in her father's nursery business during the depression.
A keen traveller, she met her future husband Arthur on a Pacific Island cruise in 1939. They married and were dairy farmers until retirement.
The family plan to celebrate again tomorrow - Ms Bayes' actual birthday - with a family lunch, happily coinciding with Mother's Day.
Those celebrations are unlikely to be as auspicious as Ms Bayes' 100th birthday. Ms Bayes' letter from Queen Elizabeth II that year - sent to all Commonwealth citizens who reach the 100-year landmark - was followed by a visit from Prime Minister John Key, coincidentally on a publicity trip to Whangarei that day.
The New Zealand citizen who holds the record for longevity was Florence Finch, who died in 2007 aged 113.