Use difficulty as a guide not just in selecting the overall aim of your company, but also at decision points along the way. At Viaweb one of our rules of thumb was run upstairs. Suppose you are a little, nimble guy being chased by a big, fat, bully. You open a door and find yourself in a staircase. Do you go up or down? I say up. The bully can probably run downstairs as fast as you can. Going upstairs his bulk will be more of a disadvantage. Running upstairs is hard for you but even harder for him. […]

This is a good plan for life in general. If you have two choices, choose the harder. If you’re trying to decide whether to go out running or sit home and watch TV, go running. Probably the reason this trick works so well is that when you have two choices and one is harder, the only reason you’re even considering the other is laziness. You know in the back of your mind what’s the right thing to do, and this trick merely forces you to acknowledge it.

From How to Make Wealth by Paul Graham