Daniel Ricciardo said he never asked himself what might have been if he was still driving alongside Max Verstappen at Red Bull this season.
Ricciardo joined Red Bull in 2014 and was Verstappen's teammate from mid-2016 until he left for Renault at the end of 2018.
Verstappen won the championship at Sunday's Abu Dhabi Grand Prix, Red Bull's first F1 title since 2013.
Speaking to ESPN on Friday night ahead of that race Ricciardo, who now races for McLaren, said: "Looking at Max this year, I 100 percent don't feel any envy, jealousy or weirdness to him or the team.
"Weirdly enough, I'd be very, very happy for them!"
Ricciardo was Verstappen's most competitive teammate at Red Bull, with the team cycling through Pierre Gasly, Alex Albon and Sergio Perez in the years since.
The Australian said he stopped thinking about that chapter of his career a while ago.
"I don't have any [regrets]. People probably thought 'I wonder what Daniel thought this year, would he also have been fighting for a championship?'.
"Up until right now I haven't actually thought about that. I think it's hard to answer in a way that... the easiest way to say it is, I really did, and not in a negative way, I detached myself from it.
"Once I closed the book with Red Bull I really tried to put all my energy into the next part. I really didn't have any over-hanging, like, what could've, what should've."
Ricciardo, who claimed McLaren's first race win since 2012 at September's Italian Grand Prix, said a big part of the decision he made in 2018 was making sure he could live with himself if Red Bull went on to win the championship after he left.
"I remember through the decision process I even told myself, 'can I live with myself if, in 2019, Red Bull win the championship? How is that going to make me feel?'"
"So I'd already addressed those things. And now we're obviously a few years removed from that. I definitely don't have any... I'm not really that spiritual or whatever you wanna call it, but I do think things happen for a reason.
"From that I don't really feel like if I stayed maybe things would have been different. I don't really feel that. I don't think like oh 'what could have been, I could have been double world champ by now', or whatever. I used to think like that when I was younger but I feel like obviously the decision I made, I gave a lot of thought and I had to move on with that."
He added: "This wasn't even for that specific situation, but my dad told me something when I was young. He said 'if you look too far back, you'll get a sore neck'. It's true, once you make a decision and once you make a decision you thought long and hard about, I think it's important that you move forward with that".