There’s a moment in Free Solo during Alex Honnold’s historic, rope-less ascent of El Capitan when the audience sees cinematographer Mikey Schaefer doubled over, so sick with anxiety that he’s unable to watch what’s happening. It’s a powerful moment. And, after speaking with Co-Directors Jimmy Chin and Chai Vasarhelyi, it seems to accurately sum up what sounds like the most stressful production we’ve ever heard of — a production they weren’t even sure they wanted to take on: