"What's that line, it was either Rilke or Einstein, believe it or not, but it was something about when you can walk with the paradox, when you carry real pain and real joy simultaneously, this is maturity, this is growth."
But despite this sense of loneliness, the actor said he's found connection and friendship through his decision to go sober in 2016.
The newly-divorced actor spent 18 months going to regular Alcoholics Anonymous meetings, abiding by the group's principles of abstinence from all mind-altering substances.
"I had a really cool men's group here that was really private and selective, so it was safe," he explained. "Because I'd seen things of other people who had been recorded while they were spilling their guts, and that's just atrocious to me."
The lifelong smoker also made the decision to cut out cigarettes, substituting tobacco with nicotine-flavoured gum.
"I don't have that ability to do just one or two a day," he said of his past smoking habit. "It's not in my makeup. I'm all in. And I'm going to drive into the ground. I've lost my privileges."
In the past, Pitt admitted to smoking marijuana on a daily basis amid his first marriage to Jennifer Aniston.
In 2019 he told the New York Times, "I spent most of the '90s hiding out and smoking pot. I was too uncomfortable with all the attention."
He and Aniston divorced after Pitt met Jolie on the set of action thriller Mr & Mrs Smith, in which they played an on-screen couple.
The couple married at their French chateau in 2014, but by 2016 Jolie initiated divorce proceedings, which were finalised three years later.
