The world needs more women filmmakers, so we have to keep encouraging ourselves and one another, and eventually things must get easier for us.

I've always been a fiction filmmaker and I've been heading in the direction of fiction filmmaking, doing documentaries along the way.

The world of extreme sports is also one of the big businesses. Kids might think that snowboarding is the ultimate freedom, but this freedom is being marketed to them by commercial sponsors.

Extreme sports tricks are becoming increasingly complex, the courses ever more challenging and crashes all too common.

There's a theory of accidents that I studied when I was making a film about nuclear weapons: you can never eliminate accidents, because the measures you introduce to prevent accidents actually produce more accidents. That's certainly true of this sport; you're flying over 40 feet of what might look like snow, but it's hard as ice, it's as hard as pavement. You're doing acrobatic spins and tricks, 40 feet above pavement, essentially. There's been more accidents since, and there are going to continue to be more accidents, that's the nature of the sport.

I think we've reached that point where we understand medically what we are doing to ourselves with these sports. In football, it's kind of hard to get the access that you want for the story and, of course, it's very long-term: the effects of the repeat concussions really don't hit until decades afterwards, whereas the traumatic injuries in extreme sports are very immediate. I realized Traumatic Brain Injury was a fascinating and important story that not had been told very much. I wanted to know more.

I love my work, apart from when it's driving me crazy. But I get to be interested in stuff and think like a filmmaker as I'm buzzing about the world and then see an opportunity to make a film, and then make it happen.