"I don’t think you ever have to grow up. You just have to stop being an asshole."

Wise words from the bearded bundle of cheerful neuroses that is Josh Radnor, the man who met your mother, made a film called Liberal Arts and brought it all the way to England for Sundance London. Chatting to us before and after the UK premiere of his campus mid-life crisis comedy, he explains what it's like to go back to your old university, the difference between acting on TV and writing/directing your own film, and why Elizabeth Olsen is so amazing.

Here's what he had to say:

With Jason Segel and Neil Patrick Harris making their names outside of How I Met Your Mother, how do you find your career as an actor versus writer/director? Would you appear in a superhero blockbuster, for example?

Hopefully Liberal Arts will out-gross The Avengers and become a massive tentpole movie. What, why are you laughing? Stay for the end credits – there’s a scene that lays the foundation for the sequel! (Laughs) As an actor, I’m open to different things, but as a writer-director I tend to gravitate towards smaller stories. It’s nice to exploit your own strengths, but I’m trying not to write a role for myself in my new film so I can just experience making the film from behind the camera.

How did you go from How I Met Your Mother to writing, directing and starring in your second feature film?

I always wrote. Rather than twiddle my thumbs or drink too much when unemployed I decided to write a lot. As an actor, you have to wait for permission to act, but you don’t have to wait for permission to write, so it was something I really enjoyed. I started off writing short stories and then scripts, and then I wrote Happythankyoumoreplease while filming How I Met Your Mother and didn’t know I was going to direct it. Then I did direct it and I fell in love with directing, which opened up this whole new door for me. I knew I wrote the role for myself so didn’t want to give it to someone else and I ended up doing all three. But it was back-breaking to do so much of this movie. It was exhausting! I’ve glossed over how hard it was, but I’m happy with the movie and happy that I did it. 

Which of the three roles do you enjoy the most?

Well, in some ways acting scares me the most because it’s the most vulnerable. So when I’ve managed to throw out my bad takes and choose the least horrible ones that’s a great feeling. But there’s also something satisfying about sitting in a coffee shop and dreaming up this story and moulding and shaping it and taking the audience with you where you go. It’s like conducting an orchestra and having all these instruments available to make a bigger sound, but there’s still something thrilling about playing the instrument.

How was the writing process after your first film?

After Martha Marcy May Marlene and Silent House, Elizabeth Olsen seems to be everywhere, but how did you end up casting her? 

I hadn’t seen those other movies when I cast her. I just thought she had a number of different qualities that were perfect for the role. She has the perfect lightness of spirit – an adult level of sophistication mixed with this youthful enthusiasm. There’s certainly no evidence in those other movies that she’s so charming and light, but put them altogether and there’s evidence of a real talent.

In the film, there's an unnamed book that one character keeps reading. What was it?

The big book that Dean is reading is Infinite Jest by David Foster Wallace. I didn’t want to name the book because the characters know what the book is – they don’t have to name it. I wanted them speak in that shorthand. 

What's your own relationship with your uni (Kenyon College, Ohio) like?

It’s weird. Kenyon and a lot of colleges are sort of frozen in time. There’s an institution there and that backdrop stays the same. My memories of going there are so incredibly vivid – but I went back to show Happyhtankyoumoreplease and felt a lot older. I couldn’t understand why. There’s an arrogance to youth because you don’t realise that time is passing. I realised the other day I’m now too old to be called a prodigy anymore! It’s no longer “the prodigiously young Josh Radnor…” It’s “adult Josh Radnor…”

I read a definition of the word suffering, which said that suffering is just wishing things were different to the way they are. Making this film was like a dialogue with myself on some level about not losing my mind about ageing and growing up, but rather looking into it and working out what gifts were there for me. 

And finally, how does it feel to be at the very-first Sundance London? 

It’s a real thrill to be invited here and to be in such a small collection of the films from the festival. This is the most fun for me; bringing it to new crowds and seeing that you don’t have to be a Liberal Arts grad who grew up in Ohio to enjoy it. It’s a very exciting exchange for me and to do it overseas? There’s a big kick to that.