"In the early days I was barely able to make it to the next power pole, but the day I did my first 2km without stopping, that was a big day."
Since then she has run four marathon-distance races and a 50km.
"I think, if I can do it, then anybody can, the biggest challenge is yourself, and that little voice in your head," she said.
"We were a nervous wreck at the beginning of those longer distances, but what you put in, you'll get out of it and once you start, it just really starts getting into you."
She is now part of the group Jogging the Powerpoles and works to its training routine.
"The biggest step was turning up.
"If it wasn't for Kerris, I really wouldn't be doing this."
Throughout her training there has been a key source of inspiration for Christie, her daughter Tui.
Eight years ago Tui suffered a serious head injury in a road crash.
"When it gets tough, I think of her and what she's been through."