[Watney's] not allowing himself to talk about it, how the despair, once you let it in, it just feels like it's going to come barreling through that door. It's all about finding those moments. We just let them come out. There's a point where Mark finally does crack. You just sort of let it feel. Matt, that was his instinct as an actor. That's where it felt, "Oh, it's going to come out because I'm finally hearing their voices for the first time." It just felt right to him.
The scene where the habitat breaks and Watney puts it back together with a tarp and masking tape really stressed me out, with the wind blowing and all he's trying to do is count potatoes. He doesn't break, but he's breaking. There are no words, but it's so stressful. How did you write that?
"The Martian" is out in theaters now.