I learn how to impact the world.
It's the idea that when people are given two choices, they will be more motivated to pick the choice that is more fun.
Ex. People would rather go up stairs that played music than an escalator given the opportunity.
If I could apply the "Fun Theory" to something, it would probably be for vacuuming. Maybe a counter to how much dirt is sucked up and it is counted as points towards a game? Something silly that would still motivate others to get as much dirt with the vacuum cleaner possible.