Preacher star Joe Gilgun opened up about his struggles with bipolar disorder during the filming of Season 2 at Comic-Con International: San Diego this year.

Preacher's sophomore season saw the Three Amigos at their lowest point. After spending much of the first season building a friendship that bonded the three into family, the trio spent Season 2 splintering apart. Gilgun's Cassidy had a particularly rough go of it -- he worked hard to massage his relationship with Jesse and Tulip only to be dismissed by Tulip and condescended to by Jesse. He also had to put down his only son after Denis became a more predatory vampire than Cassidy was willing to unleash on the world. As it turns out, Gilgun was also struggling, albeit with very different demons.

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Gilgun has always been extremely open about his struggles with mental health. During Preacher's first Hall H panel, a fan criticized Tulip's decision to sleep with Cassidy during the first season, questioning how she could ever make such a choice. Before Ruth Negga could answer, Gilgun shouted that it was self-destruction driving her.

Earlier in the panel he had also been very frank about how a battle with drugs left him with "drug-induced" bipolar disorder and a side of Attention Deficit Hyperactivity Disorder. In the ensuing years, he has continued to be totally honest about his experiences in various interviews and appearances, and this year's SDCC press conference was no different.

When a reporter for Bleeding Cool asked what was something over the years that had been difficult for any member of the cast to film, Gilgun responded that most of Season 2 had been particularly rough.

"I was a bit depressed last year. I've got bipolar and last year... it was a tough year last year. It's not to say I didn't have a good time. There are moments where, in my career when I get that way where I honestly believe that I've forgotten how to act. Like I can't fucking -- I can't even begin to put it into words how terrifying it is, that feeling. It's so fucking real when it's happening. I remember standing with Sam [Catlin] at one point and I think I said something like: 'Tell me something, Sam, that'll make me feel better because I feel like shit today. I feel like I'm doing a terrible job.' [And he said,] 'You're not doing a terrible job.'"

Gilgun went on to reveal that, in those moments of crisis, he found himself leaning on his cast members for support. As always, he reiterated his desire to remain open and honest about his mental health battles.

"...it was those moments I had to rely on the people around me and I fucking believed it man. ... When anyone said anything different, I was wondering what their agenda was. What are you trying to get out of this by telling me bollocks, because I don't believe it. So it were during the filming of last year including the panel we're about to do. It was really difficult. I was in a bad place. Those are the moments that are difficult for me filming. I do wanna be honest and open about the depression, and I got a lot of good feedback since doing it on the first panel when I spoke a lot about mental health. It's a big deal for a lot of people. I wanna carry on [with] that. That's honestly how it can be. There are days where I just can hardly cope and I just battle through. You can do it, you can fucking do it."

In recent years and months, mental health has dominated public conversation in an unprecedented way. Deaths of major celebrities like Carrie Fisher, Anthony Bourdain and Kate Spade, all of whom struggled publicly and privately with the likes of depression, bipolar disorder and other issues, have amplified the call to destigmatize mental health.

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Gilgun's characteristic frankness goes a long way toward raising awareness and possibly making those suffering from the same problems feel less alone or more capable of overcoming their adversity. At the end of the day, Gilgun is simply an example of someone who's managing an illness day by day while simultaneously achieving great heights. If his candor can inspire someone to seek a similar state as their new normal, he'll have made an immeasurable impact beyond his work as an actor.

Airing Sundays at 9 pm ET/PT on AMC, Preacher stars Dominic Cooper as Preacher Jesse Custer, Ruth Negga as Tulip and Joe Gilgun as Cassidy the Vampire. Betty Buckley (Gran’ma), Colin Cunningham (T.C.), Jeremy Childs (Jody), Liz McGeever (Christina) and John Coyne (Allfather D’Arronique) also join the cast.