Sometimes I go people watching. Like most people, I usually do it to pass the time and imagine backstories for the faces I see. But I can’t help wondering, with each person that passes, how they decided to embark on any of the billions of choices they could make on that day.

Take this guy walking into the restaurant I’m eating at this morning. He’s wearing baggy jeans and a grey sweatshirt with a light windbreaker. Out of the dozens…