"We thought, let's just do it," Jack told The Australian Women's Weekly in 2012.
"We didn't want a large wedding, we just wanted our close family around one table for a relaxing lunch to celebrate with us," he revealed.
At the time, Natalie explained she was pregnant with her first child and wanted to keep the nuptials a secret.
"We didn't tell anyone they were coming to a wedding, so it was a huge surprise," Natalie said.
"I wore a beautiful Lisa Brown dress, it was so relaxed and amazing," she said, adding, "We loved every minute of it."
In January 2013, Natalie gave birth to the couple's daughter, Olivia, who is now seven years old.
Natalie and Jack keep their family life extremely private, rarely posting photos of each other on social media - Natalie never tags Jack's profile - and staying away from red carpet events.
But Natalie has spoken about her love of motherhood, as well as how she balances travelling for work with her family life on the Gold Coast.
"I'm absolutely loving being a mum. I feel very blessed to have a healthy little girl and to be living on the coast [Gold Coast]," she told The Australian Women's Weekly in 2014.
"It's gone by in a flash. I try to enjoy every little moment with Olivia."
Back then, Natalie said the couple had "no plans at this stage for a brother or sister for Olivia".
"I have the best of both worlds," she said at the time.
"But as any mum will tell you it's about finding that balance."
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This story originally appeared on our sister site, Now To Love.