At the moment, the bubbly St Kevin's College pupil is in "rehab stage" in training, following injury, and preparing for competition over the summer months.
She has been training every day, a total of about 17 hours a week, rising at 5.15am for swimming at 6am.
After a day at school, she will then either go for a bike ride, run, gym session or do some transition practice, with an occasional race at weekends for training.
Reubyn enjoys training, saying it keeps her busy and in a good routine, even though it means early nights to bed.
Last month, she was third in the national under-19 schools duathlon championships in Christchurch.
While leading the field at one stage, confusion on the course resulted in her going the wrong way and her hopes of winning were dashed.
But it is the triathlon which is Reubyn's major passion, having been encouraged into the sport by another Oamaru multisport enthusiast, Adair Craik.
Reubyn, who was senior girls athletics and cross-country champion and Treacy House sports captain at St Kevin's this year, has been competing in triathlons for about 16 months.
She loves travelling to events, along with the actual competition, meeting new people and catching up with fellow athletes.
Aside from injury, it has been a difficult year for the plucky young athlete, whose mother, Vicki, died after a very brief illness in March.
Reubyn is heading to Lincoln University next year, where she hopes to study sports and recreational management.
She is excited about the prospect of university life, saying it will be interesting to combine training with study and lectures.
At the moment, Reubyn had a "bit of a social life", believing it was good to keep some balance in her life.
Her aim was to secure a spot in the New Zealand under-19 triathlon team next year and eventually race on the International Triathlon Union world circuit.
Reubyn, who is coached by Shane Jones, has been doing sprint distances - 750m swim, 20km cycle and 5km run - but she would like to get into some longer distance races, to which she believed she would be better suited.
Her strongest discipline was running, largely because she had a running background, and her weakest was swimming.
She enjoyed cycling the most because it could be more social.
"At least with cycling, you can be in a pack ... and you get to see more of the countryside."
Reubyn was inspired by elite triathletes Andrea Hewitt, Gina Crawford and Debbie Tanner.
Tanner gave her a box of clothing when she changed sponsors.
