The trials involved a best-of-three race series, which Cox won convincingly, and soon after she and Waikato's Justine Hobbs were announced as the NZ Under 21 lightweight double sculls pairing.
Cox reckons she could have performed better but was delighted with the result.
"I was happy with the outcome of dominating the three races. However, I feel I wasn't pushing myself enough," she said.
"Not having a crew right on my tail didn't help but the racing should have been at a higher intensity.
"I was confident going off my results at nationals and I was the favourite to win. However I was pretty nervous as I hadn't rowed competitively since nationals in February and my competition had recently raced at the NZ University Championships."
Cox was a standout performer at the 2018 Rowing Nationals, firmly putting her in the mix for national representation.
She paired with Madison Brooke to dominate the field in the women's senior double sculls on Lake Karapiro, the site for the Under 21 trials, backing up a gold medal in the women's club doubles in 2017.
Cox also picked up the bronze medal in the women's under-20 single sculls.
While she hasn't been competing at events since then, she's been getting through a lot of work in Whangarei with her coach.
"Since February I have been training both by myself and with the assistance of Grant Clearwater. I've been training 10 to 12 times a week," she said.
"I'm really grateful for my employer at Whangarei Aquatic Centre, who has allowed me to work around my training schedule."
Cox's introduction to rowing came from an encounter with a school newsletter in 2011 and she's been hooked on the code ever since.
"At first it was just a hobby until I got my first medals three years into the sport at the North Island Secondary School Championships in 2014," she said.
"It just became an addictive sport – if you are a sucker for pain."
Now Cox has her sights firmly set on representing New Zealand out on the water. While she'll continue to train herself for the time being, the crews get together in a few weeks to finalise their preparations for Australia.
"Six weeks from now the team all meets in Cambridge for a 10-day camp before we depart to Sydney for our first series, starting June 28."