In another interview with Red Bull, Barrett was asked if 2018 was his toughest year to date in rugby.
"I wouldn't say that," he replied. "Every season is hard, every season has its ups and downs. But yeah, it was a challenging one and I felt that I made a lot of gains in some areas, and you know, building from some awesome experiences too."
Barrett also talked about the motivation of winning a second World Cup title in 2019.
"That's a big motivation for me, it's a great opportunity hopefully on selection in the squad. I just know it's such an exciting time, it's sort of four years of preparation and then the competition itself, it's seven or eight weeks.
"For some reason, the more the pressure comes on, the more enjoyable it gets. There was the case in England in 2015. So hopefully I can be part of it, and hopefully it's a memorable one."