When I was growing up and somebody like Robert De Niro had a movie come out, it was a cultural event. Because he had such a confidence and a single mission that was so intimate.

At this stage, what would be rewarding would be for audiences to want to watch.

What happens is things come to you - director, script - and if you respond to it, it's because it's tapping into some part of what's inside you, and different roles tap into different parts.

When you get divorced, all the truths that come out, you sit there and go, 'What the f**k was I doing? What was I doing believing that this person was invested in this way?' Which is a fantastically strong humiliation in the best sense. It can make somebody very bitter and very hard and closed off, but I find it does the opposite to me.

In short form I'll say it was an approach to the family and to [author] Jon Krakauer that then led to me seeming to rise to the top of the heap of several filmmakers that were trying to get the rights. And by top of the heap I mean in terms of being somebody that was trusted to do it as they said they were going to attempt to do it and that this way of doing it would be something they would be willing to allow.

My greatest interest in it was certainly not to avoid those things that were going to be controversial about the family but the interest I had in the story was predominantly what he was pursuing and not as much what he was fleeing.

The heartbreak that it might not happen wasn't something that I wanted to face with any more weight. Then, when I got the call to go ahead I never thought for a second as I was approaching it who I would get - that would come later. Again, I think the idea was that I now had the rights to make the movie and I can start writing it but if I have to wait another 10 years before I find an actor that's right for it, I'd be very happy to do that.