For years, Gary Cohn thought he’d be the next C.E.O. of Goldman Sachs. Instead, he became the “adult in the room” in a chaotic administration. Cohn talks about the fights he won, the fights he lost, and the fights he was no longer willing to have. Also: why he and Trump are still on speaking terms even after he reportedly called the president “a professional liar.”

Whether you’re building a business or a cathedral, execution is everything. We ask artists, scientists, and inventors how they turned ideas into reality. And we find out why it’s so hard for a group to get things done — and what you can do about it. (Ep. 4 of the “How to Be Creative” series.)