The 53-year-old actor said in the summer issue of GQ Style that he stopped drinking and started therapy after Jolie filed for divorce last fall.
"I do remember a few spots along the road where I've become absolutely tired of myself. And this is a big one," Pitt told the magazine. "These moments have always been a huge generator for change. And I'm quite grateful for it."
"I can't remember a day since I got out of college when I wasn't boozing or had a spliff, or something. Something," he said. "And you realize that a lot of it is, umm -- cigarettes, you know, pacifiers. And I'm running from feelings."
"I'm really, really happy to be done with all of that," Pitt said. "I mean I stopped everything except boozing when I started my family. But even this last year, you know -- things I wasn't dealing with. I was boozing too much. It's just become a problem. And I'm really happy it's been half a year now."
Pitt said he "went through two therapists to get to the right one," but is using therapy to examine his "weakness and failures" and implement positive change. He said he was a "professional" drinker when he quit alcohol.
"I had to step away for a minute. And truthfully I could drink a Russian under the table with his own vodka. I was a professional. I was good," he said. "Don't want to live that way anymore."
Pitt and Jolie, who share six children, split in September after two years of marriage and a decade together. Jolie filed for divorce after she said Pitt had an altercation with their son Maddox on an airplane, although the actor was later cleared by the FBI of any criminal behavior.
"The FBI has conducted a review of the circumstances and will not pursue further investigation. No charges have been filed in this matter," an FBI representative said in November.