I'm constantly looking to see whether I look the same as I did earlier, whether I've put on or lost any weight.

I was already devouring literature and I was the ripe old age of 15 when I decided to be an actor. I just thought plays were the most fantastic way of expressing life. I thought I'd discovered Shakespeare - 'hey, there's a new guy in town, don't know if anyone's read him.' I was just excited about the whole thing, from day one.

Solomon Northup is one of the most remarkable people Ive ever encountered in my life; one of the most amazing stories I have ever been in any kind of contact with. To not tell that story would have been disgraceful, in my opinion.

I remember being very affected by what was going on there towards the end of Apartheid. And the subject is still very pertinent, politically, to what's happening around the world today, in terms of negotiating peace talks. I had always been interested in this period of change in South Africa, generally, for a variety of reasons.

Once you click into a character, to a certain degree, you can do a lot else. You can do other stuff, then come back and click right into the character. It's sort of funny that way, the way the mind works. Once it's there, it's sort of there. For the stage, for example, all through the day, you're not onstage. You're living your life, la-la-la, then the lights go down, then boom! All of a sudden, you're in this thing. There's a kind of reflex muscle trigger that happens, and all of a sudden you're back into the role. It's just getting there in the first place that's tricky.

The thing about film is it is a very precise form. You know if you have it and you know if you don't have it. There's not really a middle bit where you're like, "I think we kind of have that scene."

The only way to be an actor is to find ways to work as an actor, even if that means doing a one-man show by a river.