There’s a new theory out there that if you want people to change their behavior, you have to make it fun. It’s called the Fun Theory. The idea was put to the test when a subway staircase next to an escalator was transformed into a working piano that plays a note each time you take a step. That day 60% more people chose the stairs just because it was fun. Of course taking the steps over an escalator is better for your health and the environment, so why weren’t that many people choosing the stairs before? Perhaps it just wasn’t fun enough.