"She's 49, so she's older than me, but she's a beacon of hope," laughs the beloved broadcaster as she shakes her booty to some of J.Lo's biggest hits for our camera.
"When I was a kid, people in their 40s were so old, but now it's cool to see women who are still really vibrant, strong and inspirational – with or without toy boys!"
But jokes and Jenny from the Block aside, the reason Stacey is celebrating is rather serious. At 45, the Hits radio star has reached the same age her mother Sue Walmsley was when she tragically died of breast cancer.
"It feels significant," Stacey tells Woman's Day. "I've outlived one of my parents, which is so weird, but Mum gave me a huge birthday gift of gratitude. I feel so grateful to be 45, alive and still really healthy, while my mum had seven really hard, sick years before she died."
Stacey – who has three kids, Hawaiki, 11, Kurawaka, 10, and Maiana, six, with Te Karere presenter Scotty Morrison, 47 – confesses she "fell apart" after her mother's death and 16 years later, she still has days where she desperately misses Sue.
She says, "Sometimes I'm like, 'Is she still dead? I'm over this!' The one thing I really feel is her not getting to be a nana. The kids had Grandparent Day at school recently and it was a little knife in my heart. I grieve for that all the time."
"It gives you an empathy, an insight into grief. I had a full range of experience I didn't have otherwise. But no matter what the age or how close they are, losing a parent is the end of a chapter of your life."
Stacey keeps her mother's memory alive by telling her children about their late gran, keeping photos around the house and marking Sue's birthday every year with a balloon release. She also honours her mum by acting as an ambassador for the Breast Cancer Foundation.
"Mum was a very community-minded person and before she died, she did stories with Woman's Day. She figured if she could help one person, she was going to do it. I always feel I'm moving with her spirit when I do things like that. When you experience grief, it helps to do something proactive.
"Things like the Pink Star Walk are great exercise and a good opportunity to fundraise, but they're also a real outlet for your emotions."
Coincidentally, 45 is also the age at which Kiwi women are eligible for a free mammogram, a "great offer" Stacey says saves lives by detecting breast cancer before it spreads. She had her first free one just before our interview and even made a video for Breast Cancer Awareness Month while having it done.
"It was really exciting!" she laughs. "Because of my family history, I've been having them since I was 28, when the machines were like squashing your boob in an elevator door, but now they're not so scary and they don't even take long.
"Sure, it's a bit weird and uncomfortable – like your breast is doing yoga without you – but it's actually scarier not to get it done. Mammograms have given me really good peace of mind."
Stacey is yet to get tested for the BRCA cancer gene, but if it turns out she is genetically predisposed to breast cancer, she'll have no qualms getting a pre-emptive double mastectomy like actress Angelina Jolie did.
She says, "My husband likes my boobs, but they've done their job breastfeeding three kids and I'd prefer to be alive!"
In the meantime, Stacey stays vigilant with regular self-checks, explaining, "It's about looking at physical changes in your breasts. There can be puckering, skin-colour changes or your boobs sitting differently. It's not just looking for lumps – by the time you feel one of those, you're a little more advanced."
Diet and exercise are also key to reducing the risk of cancer, so Stacey keeps fit by doing yoga most mornings.
"The dog usually joins me on the mat and does a little downward dog with me," she laughs, adding that she also follows a low-carb diet after witnessing some friends lose up to 15kg on it.
And it seems to be working for her, with Stacey looking flexible and fantastic as she poses up a storm in the same ghetto-fabulous gear she wore back in the '90s. The only problem is, how will we top this for Stacey's 50th birthday?
"It'll have to be a bikini shoot!" she laughs.