Field of view
Fitt's law argues that focus is as much a function of proximity as it is of attention. In other words, it's easier to interact with things that are closer to you than those that are farther out.
That sound's obvious enough. And yet, so few of us take advantage of that phenomenon.
The lesson is simple: If you want to be productive, move your priorities closer--the buttons you want to press, the commitments you want to keep, the lessons you want to absorb--and push everything else away.
It could save your life.