When British researchers adorned a flight of stairs in a shopping mall with the instruction “Take the Stairs,” it turned out that shoppers actually did. Over the course of three weeks, the number of people who chose to take the stairs increased by 190%, despite an escalator nearby. What gives? On a rational level, we know that exercise is beneficial. But our decision-making tends to be a chaotic process guided by intuition, unconscious bias and time pressures. On top of that, an estimated 80% of human behavior is automatic, with bad habits quickly becoming ingrained and remaining unchallenged.

It turns out it’s surprisingly easy to modify our aversion to energy-consuming stairs using mere suggestion. Put a staircase front and center (in most modern buildings it’s the elevator t...