Theresa Christy has the coolest job in the world. As a mathematician for Otis Elevator company, she’s spent more than a quarter-century tweaking how things go up. She also knows that the longest we’ll wait for a door to close is 20 seconds, Japan has the smoothest rides, and the average American rider is 22 lbs heavier than a Chinese one.

I caught this note from Ms. Christy about how she thinks about her job.

At their core, elevators are a mode of transportation. Serving passengers well is constrained by the number of elevators, their speed, how fast their doors open and close, and how many people can fit in a car. In the U.S., these factors come together 18 billion times a year, each time a passenger rides an elevator.

That experience is at the heart of what Ms. Christy does. From her sparse second-floor office in a leafy office park in Farmington, Conn., she writes strings of code that allow elevators to do essentially the greatest good for the most people—including the building’s owner, who has to allocate considerable space for the concrete shafts that house the cars. Her work often involves watching computer simulation programs that replay elevator decision-making.

“I feel like I get paid to play videogames. I watch the simulation, and I see what happens, and I try to improve the score I am getting,” she says.

So it’s basically just a big elevator sim.