"Yet when I watched the Ironman I realised they were people competing with no eyesight and I was so inspired I entered the IronMaori [which took place in December 2015] event, the very next day."
A strong runner and swimmer, Gunn says she found the process of cycling without the use of a right eye "a huge adjustment".
Unable to see oncoming traffic when looking over her right shoulder made cycling problematic but over time and thanks for the support of her training group, who her give her regular verbal updates on the road, her confidence has improved.
After enjoying a "perfect race" at the IronMaori -- over the half distance -- last year she was awarded the Tony Jackson Scholarship, an event package to a deserving athlete which includes entry and coaching to enter the Ironman NZ.
Training between 20-25 hours per week under the guidance of Andrew Mackay at Boost Coaching, Gunn has continued to thrive and in January completed the half-distance Port of Tauranga race in 5:14.
Her expectations today?
"I would like to start the race knowing I have a good chance of finishing," she says.
"In some ways it is more about the journey, I'm so proud of doing all the training.
"I just want to enjoy it and have a good day."
With her sister, Nikki, and her father in attendance it will make the day extra special.
"The accident had a huge impact on my family," she says.
"But my family and friends have supported me so much, so if I make the finish line so many people will have played their part in helping me get there.
"I'm in awe of anyone who makes it to the Ironman finish line -- I'm excited by the thought of hopefully joining them."