The 14-year-old competed at her first-ever Australian track and field championships last month, after initially qualifying for the 2020 titles that were later cancelled in the wake of a burgeoning COVID-19 pandemic.
One of just four athletes from the region to qualify for this year's championships in Sydney, Southern was put through her paces in the under 15 400m dash, where she finished fifth out of sixth in her heat.
With Southern's time coming in at 62.27 on the opening day of competition - she qualified with 60.32 - it wasn't the teen's best run even by her own standards.
But with the April 12 event Southern's first real experience racing at the highest level, she admits her inexperience may have worked against her.
“It was all a bit nerve-wracking but it was a good experience,” Southern said.
“I wasn't happy with my run, but it was all I could do on the day so I will deal with that.
“But it's hard when it's new and your first time. The second or third times are always smoother.”
After getting that first experience under her belt, Southern is determined to make her way back to the championships stronger than ever next season.
With the 2022 titles held in Perth, Southern's next goal is to requalify, with the St Joseph College's student needing to drop her time as she moves into the under 16 category.
“Hopefully I get to Perth. I'm only 500th of a second off the qualifier for next season so I'm close,” she said.
With training for the new season beginning in September, Southern will continue to work hard on her fitness this off-season.
Coached by Laurie Edmonston at Echuca Little Athletics, and running with Eaglehawk Athletics Club at a senior level, hard work isn't a foreign concept for Southern.
After receiving the double blow the 2020 Little Athletics Victorian championships and Australian track and field championships were cancelled within a matter of days, Southern's mind instantly turned to the following season.
Alongside homeschooling, Southern trained five days a week based on several of Edmonston's programs.
“It was disappointing, but I think my determination to get there the next year - because I hadn't qualified - kicked in,” Southern said.
Scarlett's mother Brooke said she was proud of the work her daughter had put in over the last 18 months.
“She rolled straight around and went straight back into training,” Brooke said.
“She was more disciplined than I thought she was, but I think it also kept them sane during COVID, it gave them a good balance.”