With his charity campaign “Always Keep Fighting,” Supernatural star Jared Padalecki raised ample funds for To Write Love on Her Arms, a non-profit organization that helps those struggling with depression, addiction and suicidal ideation. However, he was most keenly interested in destigmatizing mental illness following the suicide of a close friend.

Thanks to the help of the Supernatural fandom, which continues to thrive even as the show gears up for its 10th season finale, the T-shirt campaign was a rousing success.

Get push notifications with news, features and more.

Now, Padalecki and costar Jensen Ackles have joined forces. The two have set up a joint, donor-advised fund – “a junior version of a foundation,” Ackles tells PEOPLE – to support a variety of like causes that, chiefly, work to help those suffering from mental illness and mood disorders, among other causes. In the future, the pair may even decide to partner up with costar Misha Collins’ foundation, Random Acts, but Ackles tells PEOPLE that they’re just getting their feet wet with their “junior foundation” for now.

In a chat with PEOPLE, Ackles, 37, reveals his personal reasons for joining the charitable fray and how he helped Padalecki when he “went down a dark road” while filming the third season of Supernatural. Ackles also shares that he, too, has dealt with these issues and says it’s not only important to have somebody in your life to listen to you when things get dark, but also to have the courage to reach out and ask for help.

These issues are also germane to Ackles’ current plotline on Supernatural as his character, Dean, fights against the Mark of Cain which, without a cure, may overtake him completely. (Yes, don’t worry – we also chatted about what’s next for the Winchester brothers.)

Now that your T-shirt campaign has ended, what’s the next step for you and Padalecki in this joint venture?

The T-shirt was the kickoff. We see how amazing the fans are when they know that there’s a cause they can really get behind, even if it is for a shirt with a couple of ugly faces on it! The fact is, they really show up and support what we do, so we thought, “Why not try and harness this amazing power that the fans are accumulating and try to use it in a way that Misha has done with Random Acts?” We’ve changed a lot of lives doing this and we’ve gotten some amazing feedback and heard some incredible stories, and it really inspired us to see how far the helping hand of the Supernatural family can reach.

I spoke to Padalecki about Always Keep Fighting, and he revealed why the cause is so important to him. Why is it important to you?

In a lot of the ways that [mental illness has] affected Jared, it’s affected me, as well. We lost one of our crew members very recently to this, as well. With the kind of work that we do – with conventions, meet-and-greets – these interactions have been filled with stories not just of the individuals that we’re talking to but loved ones that they know. These stories just really resonated with us over the years and it just came to a tipping point where we thought that there’s something that we should be doing and we can’t ignore that anymore.

If we can help in any way, then I believe it’s our duty as human beings and as people that are in a position to do so. There are people out there that are fighting that could use the help and use the encouragement and inspiration, and those are the people we’re trying to reach.

Jared described a situation to Variety when he kind of broke down during the filming of season 3 and that you helped him through it. Can you give me your side of that?

I think it’s that he had gotten taken away from his life that he had known, which was hanging out with his buddies and working a couple of days a week on Gilmore Girls and having a support system around him. He was 22 years old when the show yanked him away from that life and basically put him up in a city and in a country that he was unaware of and unfamiliar with and made him the star of a TV series, which is a lot of pressure. You look around and there are 180 people relying on you to do your job so that they can do their job.

After a couple of years he just got really, really homesick and he missed his family and his friends. He missed his life. It just got to him. I’ve been a part of several TV shows where I’ve just seen people crumble under the pressure. It’s not that they’re weak – it’s just, at a certain time they’ve got to take a break. And Jared pushed himself a lot harder and a lot longer than most 22 or 23-year-olds would’ve at that point in their lives, and he just needed some encouragement.

He went down this kind of dark road, mentally, and he was very fortunate to have people around him. It wasn’t just me. I mean, I happened to be maybe a stronger voice in the whole thing but he had friends, crew people, producers, friends, family he was able to reach out and say that he wasn’t in a good way.

He actually asked for help, and I think that’s a big thing that people are scared to do. Luckily, I was right there. It really established a good support system early on, between the two of us. There have been seasons or months where I’ve really been down. Even last year, when my daughter was about 7 months old, I was away from her and the story line that I was doing was really dark. It was taking its toll on me. I was able to have that friendship Jared and I had established for so long and I was able to talk about it with him and that really helped. He didn’t even really need to say anything.

I think a lot of people just need somebody to listen to or just need somebody to listen to them. We’ve established not only a good working relationship but a good friendship and also a good support system with each other.

Speaking of outside forces you can’t really control, is the Mark of Cain something that Dean will ever truly be able to fight off himself, through sheer force of will, or is a cure the only thing that will do? How will that play out, leading up to the finale?

As we saw with the episode with Cain, where he and Dean have their big showdown, you see that somebody who has been living with this Mark for centuries is still not able to overcome its power. Cain, when he pleaded with him, “Tell me you can stop this,” it wasn’t him telling Dean to stop – it was him trying to see if it was even possible. He made it seem to Dean as if there was no hope.

Being as stubborn as Dean is, he will continue to fight and try to figure out a way to deal with this, and if there is no cure, then he’s going to fight until he can’t fight anymore. Unfortunately, with this particular character, when dealing with something that he is solely responsible for, he doesn’t like to ask for help.

This goes back to the real-life thing we’re talking about – when you bottle it up, when you try to go it alone the consequences can be pretty detrimental. It’s a great thing to have a support system of people willing to fight with you and fight for you. You just really need to allow that to happen.

As the season starts to wind down at the end, you’ll see that split in the road where Dean goes down his own path and refuses the help of other people, but you see that they’re not willing to allow him to do so. They start helping him behind his back and it becomes a very tense situation. When it all comes to a head, it’s a pretty scary thing.

Every season, it seems, the boys take turns saving each other. I don’t want to say it’s expected that Sam will save him, but is there a possibility that Sam won’t be able to save him? Will somebody else have to step up to the plate?

Everybody’s expecting Sam to save the day, but I would say that, in true Supernatural fashion, we give them what they want in a way that they’re not going to expect it. Will Dean be saved? Probably. I would imagine. Or, at least, somewhere down the line he’ll be saved. But it won’t be in the way that people are expecting it to be.

Supernatural airs Wednesdays (9 p.m. ET) on The CW.

RELATED VIDEO: Jared Padalecki Cancels Appearances: ‘I Am In Desperate And Urgent Need Of My Family’