When I finally got to go ride the mountains in Japan, it blew my mind.

The Tokyo Dome Big Air contest (in 2003) was my first trip to Japan. I think I won it with a double back or something. Those events were fun. I was underaged, like 19 or 20, and going over to Japan in the very beginning was insane. It was amazing.

Apart from those other riders there is a whole production team [ of The Fourth Phase] behind the cameras too, hauling hundreds of kilos of fragile and awkward filming equipment up those same frozen landscapes. They're the real heroes.

Bryan [Iguchi] had this beautiful philosophy about our connection with these incredible cycles. There's a line from one of his poems that always stays with me about 'This process we follow; this cycle we ride' and it's almost become a strap line for the film.

There's no doubt 'normal' is changing - spring actually came a month early in Alaska, for example, and we had to stop filming.

I've been to Japan so many times, but I still constantly stumble across things that are so foreign to me.

If we want authenticity we have to initiate it.