"I'm all good. I'm at peace with it. It is what it is," Sopoaga said.
"I've made a decision for myself and my family and that's all you can do in this game of life. I've got one more last crack with the Highlanders and I'm going to have a ball."
Sopoaga said he would be doing everything he could to lift the franchise in their hunt for their first title since 2015. "I'll be chasing that for sure and doing everything in my power to help the team get over the line."
Whether they get there or not will remain to be seen. However, the former All Black was also set to go into the season with the mentality of a mentor.
Sopoaga's exit after the 2018 season provides an opening for the Highlanders' 22-year-old back-up Fletcher Smith to stake his claim to the starting role from 2019, and learning as much as he can from Sopoaga definitely won't hurt his case.
"For the young guys underneath me, just kind of give them as much of my knowledge and as much of my experiences as I can and help them through, because it's a pretty tough task being a 10 at Super Rugby, especially in New Zealand.
"You want to leave the place in a better state than you found it."
Since making his debut at Super Rugby level for the Dunedin-based franchise in 2011, the No10 has scored 701 points in seven seasons. Although injuries hampered his campaigns in 2012 and 2013, he saw regular game time in the following seasons in which his game flourished and earned him a debut for the All Blacks in 2015.
Although he's walking away for now, Sopoaga wasn't turning his back on the Highlanders. When asked about a possible return in the future, he told the Herald on Sunday, "you can never say never".
"You've just got to look at someone like [Crusaders' first five-eighth] Mike Delany, the old grandad. He's still kicking around Super Rugby at 35.
"I love the Highlanders and everything they've done for me. It's a special team and a special part of who I've become, so I'd love to come back at some stage and be an old battler just hanging in there."
The Highlanders begin their campaign for the 2018 season on February 23 at Dunedin's Forsyth Barr Stadium against the Blues.