At Pixar, we do a million versions of the movie, and every one of them goes through their awkward teenage phase where it's terrible and doesn't make sense, and we just keep working on it.

Once you get into a feature, whether it's a sequel or an original one, you have to start all over again, and you're creating a world, creating new characters. You're also tracking emotions. You're trying to create emotion and create a character that you can fall in love with for two hours.

I think we make the movies, initially, with the one movie in mind. But we do love the characters, and so we kind of miss the characters when the movie is over. But I think what happens is, every now and then you realize there's more to tell, or an idea comes up.

There's some real dark days where you just feel like the story is falling apart in every one. Just keep moving forward, even when you are bluffing, even when you don't quite know what is going to happen next.