"I thought okay, it's just one of those normal accidents. Even though at the time it didn't sound normal."
And it wasn't normal.
Half an hour later, Lara got a call from her mum who told her Harper couldn't move her legs.
"I said 'you need to take her to the hospital ASAP'."
The Heta whānau live in Kaukapakapa, so Lara organised for Harper to be airlifted to Starship Children's Hospital in Auckland.
Lara and Harper's dad Hayden met her there.
Thinking back to that time still hurts.
"Learning that your child was to never walk again, it still gets me now. I hold it in a little black box and don't open it up because it can't change."
Lara said once they realised it wasn't going to change, they focused on getting Harper moving around. Like most kids, all she wanted to do was get up and do something.
"Once we got to the rehab facility. She was in a wheelchair and learning to move about and go about her daily life as best she could.
"She was really brave and really strong. Being 7 she had no idea what her future was to look like and she just took it in her stride and smashed all the challenges to get us home."
Harper has continued to smash challenges.
She was the star performer at last year's Attitude Awards, dancing with others in the opening performance of the nationally televised event.
Like a typical 12-year-old, she also loves hanging out with her friends - and biking, thanks to an attachment that turns her wheelchair into a three-wheeler.
"I really enjoy kapa haka because I love singing and I love the arm movements and I like being included a lot," Harper said.
"And I think being in kapa haka has given me a lot more confidence. We've created a whānau being in the group."
Harper said her ACC recovery partner Justine, who also has paraplegia, had been a "big help".
"She's definitely one of my idols, she's definitely someone I can look up to," Harper said.
Lara agreed.
"Justine has been a part of Harper's whole journey, in terms of equipment, starting new sporting activities, adventures - because when you become a person in a wheelchair, life looks a little bit different."
Lara said she and Hayden have continued to encourage Harper to be the best she can be.
"Everyone has somewhat a disability whether it's in their mind, and that's just what she thinks too. It's like 'well you can see my disability but I can't see yours'."