I did a production of 'Journey's End,' an RC Sherriff play about World War I, at the Edinburgh Festival. I was 18 and it was the first time that people I knew and loved and respected came up to me after the show and said, 'You know, you could really do this if you wanted to.'

The thing about running is, if I run in the morning before work, I feel like I'm ahead of the day. Whatever work I've done in terms of preparation or research or thinking about the scene or the character, it all kind of crystallizes in that moment in the morning. And sometimes I have the best ideas then.

If you play it straight it's funny - the best comedy is always played straight down the middle. The adjustment is understanding from the screenplay that a moment is hilarious.

What I learned in Guinea is that we are all responsible for the state of our world. The world - and the system by which we trade, share, cooperate and conflict - is clearly not working. We are only as strong as our weakest members. UNICEF is run at every level by strong, relentlessly energetic, deeply capable people who use that strength, energy and capability to help those who need it most: the weakest, most disadvantaged women and children of our world. All I can do now is help make people aware of what is happening, of what they are doing. That is all that I can do. For now.

I am desperate to do a comedy now.

Well, I don't know. When I signed my contract, I signed to play Loki in five more Marvel movies, but they were unspecified. So, if there will be more movies or not remains to be seen, but I like the idea of Loki turning up in the shadows when people least expect him, but you never know these things, the world changes and the things change, but I feel like I know who Loki is, so I wouldn't mind.

I wish I hadn't worked so hard; I wish I'd had the courage to live a life true to myself, not the life others expected of me; I wish I'd had the courage to express my feelings; I wish I had stayed in touch with my friends; and I wish I had let myself be happier. It's an extraordinary list of getting in your own way, isn't it?