I don't make 'issue' films. I like making films about rebels or pioneers or people that are doing something.

I don't want the people I'm with on this journey to feel like I'm filming them all the time. I don't want them to constantly feel as though they're being watched. So I will have the camera ready at all times, but I will only film when something is really worth filming. Those are the moments when the person being filmed is usually not aware of it.

The magic of documentary is that I keep being surprised and amazed by the things I film.

I want every scene to feel electric and I try to finish the filming period with a clear trajectory: a beginning, a middle, and hopefully an end.I hate "fly on the wall." It infers that I don't relate to the people we're with and that I don't get affected by events. I like it when people talk to me. I never say things like "Don't look at the camera" - how bossy!

I watch mainly fiction. The films I like watching are films where you see people change, like with Boyhood. You see a moment in someone's life where it's a breakthrough. For me, the breakthrough in Boyhood is that amazing moment right at the end when he finds somebody he can feel relaxed with, and who will maybe be a friend for the rest of his life. I like that it doesn't end in a love affair or marriage. It just ends in, "Wow, I found people I can relate to for the first people in my life. These people accept me, I like them."

It makes it very easy. I have a beginning, middle, and end, and I don't film for long - about 20 hours usually for a two-hour film - so it's easily watchable in a week for me and the editor. Once I know who the characters are, I only film those characters, unless somebody else forces their way into the film by a scene happening to them or we meet them by chance.

I don't have any advice at all. I think we all make the films that reflect the kind of people we are; we all make such different films. There's not just one way of doing it.