Affleck's first stint in rehab was in 2001, but he has been open about being exposed to alcoholism throughout his childhood due to his father Timothy's own battle. In 2012, Affleck spoke to Barbara Walters about his difficult upbringing.
“Yes, he was an alcoholic. . . . I did know that as a child," Affleck told Walters about his dad. "He drank a lot. My father was a -- what did they call him -- a real alcoholic. He, you know, drank all day, drank every day, and to his credit, he got sober, ultimately, and he’s been sober for several decades, which I think is pretty impressive.”
"But I had a good friends -- I had Matt Damon, my brother's a great guy," he added about how he dealt with it. "I had a nucleus of friends that I grew up with and I had support from."
In a 2014 interview with Playboy, Affleck once again opened up about his father's alcoholism -- and how it affected his own choices as an adult.
"My dad had ambitions but also a troubled life," he shared. "He had a lot of tragedy in his family, a lot of pain, and he drank to ease some of that pain. Once you start drinking too much, it's hard to fulfill your ambitions. He became a pretty serious alcoholic. He's sober now. He's been sober for 20 years, and I think it's incredibly admirable. But when he was drinking, he fell apart. My mom kicked him out, and then he was kicking around and living on the street."
"That was a formative period for me," he continued. "It caused me to obsess about success and money, because my dad ran out of money and got kicked out of his house. I obsessed about how important money was. It got wired into my DNA, and that obsession probably caused me to do some movies I shouldn't have."
As far back as 1998, Affleck was already aware of his drinking habits. In an interview with USA Weekend, he said he had stopped drinking alcohol and candidly reflected on his behavior when he was under the influence.
"I started regretting some things I did when I was drunk," he admitted. "It's funny to be obnoxious or out of control, but then it's like, 'I think I hurt that person's feelings. I made a fool of myself' or 'I didn't want to kiss that girl.' I have almost no inhibitions, so it's dangerous for me."
Three years later, in 2001, Affleck's publicist confirmed that the two-time Oscar winner had entered a 30-day residential rehabilitation program for alcohol abuse. People reported at the time that actor Charlie Sheen actually drove Affleck to Promises Treatment Center in Malibu.
"I went to rehab for being 29 and partying too much and not having a lot of boundaries and to clear my head and try to get some idea of who I wanted to be," he said. "It was more a 'let me get myself straight,' before it became a rite of passage."
But in a January 2017 interview with The Guardian, Affleck did acknowledge "mistakes" in his past.
"I’d always had a strong idea about my values and the direction I wanted to be headed in, then I ran into getting famous and it totally spun me around and I flailed around for a few years," he reflected. "When you’re a young man in your 20s, part of that is making mistakes and learning from them. I just made those in front of everybody, rather than privately. There’s stuff I look back on and kind of cringe at but I always tried to treat other people well. My parents imbued that in me and the mistakes I made were mostly just of the embarrassing kind.”
Still, Affleck hadn't yet gotten a handle on his struggle with addiction. In March of that same year, he revealed in a Facebook post that he completed treatment for alcohol addiction, thanking his estranged wife, Jennifer Garner, for her support.
"I have completed treatment for alcohol addiction; something I've dealt with in the past and will continue to confront," he wrote. "I want to live life to the fullest and be the best father I can be. I want my kids to know there is no shame in getting help when you need it, and to be a source of strength for anyone out there who needs help but is afraid to take the first step."
"I'm lucky to have the love of my family and friends, including my co-parent, Jen, who has supported me and cared for our kids as I've done the work I set out to do," he continued. "This was the first of many steps being taken towards a positive recovery."
Clearly, Affleck still has Garner's support. The 46-year-old actress drove him to rehab on Wednesday afternoon, ET previously reported. Garner was photographed arriving at Affleck's Pacific Palisades home looking visibly upset, and later, the former couple -- along with the actress' bodyguard -- were seen driving away from the Argo director's home. Affleck sat in the backseat, looking distressed.
A source tells ET that Affleck has indeed fallen off the wagon when it comes to sobriety, but not for lack of effort.
“Ben gave it his all, but sadly he wasn't able to sustain a sober lifestyle," the source says. "We were all rooting for him, but his addiction got the best of him again. He went from taking the steps he needed in life to heading back to his old ways and, for those of us that love him, it was devastating to see him lose the battle.”
But the source says Affleck definitely still has friends and family in his corner.
"Ben’s real problem is that he repeatedly gets it together for the sake of everyone else and now it's time for Ben to do it for himself," the source notes. "Ben has so much love and support and he is so strong. We have faith he can turn things around and live a healthy life.”
For more on Affleck's recent troubles, watch the video below: