The 35-year-old Irish star opened up during a panel at a movie convention in San Diego featuring the update of Fright Night.
When a fan asked whether he preferred his earlier starring roles or his more recent character parts, Farrell said that in the past six years, he "reconnected with the mystery of the whole thing and the imagination of the whole thing and how much fun it is to be an actor".
"I came to success really quickly in relation to most other actors," he said.
"The idea of how fast the chaos around me took grip, it's insane. And I, myself personally, I lost sight of why I went to my first acting class when I was 17 in Dublin... I lost sight of that through this good fortune I was experiencing in Hollywood.
"So in the last six years, I reconnected with the Colin who was 17. It's a lot of fun to do what we do. It's such a fortunate place to find yourself."
He plays the vampire-next-door Jerry Dandrige in Fright Night, a reimagining of the 1985 horror classic that's set for release on August 19.
Farrell also spoke about his role in the reboot of Total Recall. He plays Doug Quaid, the same role originated by Arnold Schwarzenegger in the 1990 original.
The film also stars Jessica Biel, Bryan Cranston, Bill Nighy, John Cho and Kate Beckinsale and is set to open next summer.