Farrell, 33, says he finds the whole Irish drinking culture "boring."
"Now – two hours in the pub, then I get bored. I was at that party for long enough."
Like many an Irish person before him, Farrell says he started drinking really heavily because he was trying to pretend he didn't care about success.
He says he didn't feel "worthy" of his movie career.
"Giving up alcohol has put more focus on my career. I'm a lot more appreciative over what I have. For years I was adamantly trying to show that I wasn't worthy or that I didn't know why it happened to me. I enjoy it a lot more now," he says.
"I just wanted to stop drinking. I was done with it, I was tired of it, I wanted to get off the treadmill.
Colin has previously admitted he used to drink so heavily, he worried it would kill him.
He said: "I'd been drinking since I was 14. I was pretty sick. At the beginning of recovery I found it really hard.
"For me there was no choice. It was tough but I was dying. I was struggling not to have a complete meltdown. I was just gone. I'm glad I'm out of that cycle, I'm very lucky.”