Koroisau has also revealed he is on a self-imposed alcohol ban this season, which he believes has led to his strong form.
The ban on alcohol came up after his COVID-19 breach during last year's State of Origin series.
It was believed his Origin cards could have been stamped never to play again following the incident, however, the Penrith star, who was a major driving force in the club's 2021 premiership win, was selected in Brad Fittler's squad for this series and ultimately started ahead of Damien Cook.
He told AAP that his alcohol ban has turned him into a much better player.
"I'm at a good spot in my life with no drinking and I think it's showing in my footy too," he said.
"When I was younger, I was always (drinking) and everyone around me was.
"It was one of those things that was just part of life when you were playing footy.
"But stopping has been really good. You don't ever have those hungover days or wasted days where you can't really get up or anything."
While fellow star recruit Isaiah Papali'i has reportedly raised the idea of not joining the Tigers in 2023 following the axing of Michael Maguire, Koroisau told News Corp that he was committed to his move to Concord.
“It’s all good for me. I’ve made my peace and committed to the decision so I wouldn’t want to back out anyway,” Koroisua told the NCA NewsWire.
“I didn’t even see what happened on Saturday.
“Honestly, until I get there next year, I won’t be thinking about them too much. It is what it is on the field and they’re obviously having a bit of trouble on the field at the moment, but I’ll worry about that when I get there.”