"And even though I would probably change a few things if I had my time again, there's not anything I regret over that period."
Kelly has been struggling with a knee injury in recent times and has been forced to change his driving style this year to accommodate it.
"I've had knee surgery twice this year, and it's been a decent battle," he added.
"Although, there have been positives for having a dodgy knee.
"I had gone 20 years without perfecting left foot braking, and at SMP this year I had to left foot brake all weekend.
"By the end of the weekend, I'd gotten pretty good at it. But in such a competitive sport that's not something you want to develop during an event."
Kelly joins fellow Supercars veteran Jason Bright, who announced he too was stepping away from fulltime driving in 2018.
While Bright intends to be a co-driver next season it is unclear if Kelly has the same aspirations.