Michael Cera: The A-list actor talks chickenpox, learning Spanish and why he'd love to work with Mike Leigh

The chickenpox and 'Ghostbusters' got me interested in acting When I was about four, I think, I got a severe case of the chickenpox and ended up watching Ghostbusters over and over, incessantly. When I was nine, I started to do drama classes, a teacher encouraged me to get an agent, and from then on I just started auditioning.

Making 'Superbad' felt like hanging out with friends It was an amazing film to work on because it never really felt like this big-budget film, even though it apparently was pretty expensive. There didn't feel like any pressure, everyone was laughing and doing things which were fun, and time just flew by. It feels great to work with people and make them laugh.

I spent most of my time during the filming of 'Juno' hanging out in my hotel room We were shooting in Vancouver and most of my scenes were at the beginning and the end of the shoot, so I had this huge pocket of time where I had nothing to do. I had a keyboard in the room, so I was able to spend time playing that. Jonah Hill came to visit and we played a lot of video games and wasted time. I did everything you could do in Vancouver. It was the first time I'd lived on my own, I was 18 and just figuring what that was. It was a lot of fun.

Learning Spanish was for my own personal gain more than anything It wasn't compulsory for me to learn it for [my new film] Magic Magic, I just wanted to go to Chile and study Spanish down there. Magic Magic [which was filmed in the country] gave me a good excuse to spend a bunch of my time and energy learning the language. It was also a way for me to will the project forward. We hadn't got all of our funding, so I found that learning Spanish made it more pressing to me that we find the money and make the film.

When picking projects, I prefer to focus on who the director is, not the genre of the film It's important to see whether it'll be a good collaboration and whether something interesting is going to come of it. In terms of directors I'd want to work with, I really like Michael Haneke a lot; it would be amazing to work with him. And I love Mike Leigh – his characters and writing capture so much humanity; but I don't think he ever hires non-English actors.

It's a good feeling to be critical of your own work If you're not totally self-loathing about it, that is. Taking pleasure from hating on yourself can be productive to see what you would have wanted to do differently.

Being in the public eye is difficult to adjust to It happened to me really quickly. You suddenly have to deal with problems which are not normal problems. When somebody is pointing a cameraphone at you, how do you adjust to that? Your actions are limited; you can either find some spiritual peace within yourself or have no problem with it. You also never know if you're just being paranoid, which is probably the case a lot of the time.

Playing music for a living seems like it would be a lot of fun For me, time really wastes away when you're playing music, be it with friends or just at home. I guess if I had to choose either to be a bass player or an actor, I'd probably choose acting out of loyalty. I just don't think I could pull it off as a full-time bass player, and that lack of confidence would make me choose acting.

Michael Cera, 25, got his big break playing George Michael Bluth in 'Arrested Development', aged 15, before 'Superbad' (2007) made him a star. His latest film, psychological thriller 'Magic Magic', is out in selected cinemas and on Virgin Movies now, and on DVD from 28 April