Quoting Paul Graham:

if your main goal is to make money, you can’t usually afford to work on what interests you the most. People pay you for doing what they want, not what you want. But there’s an obvious exception: when you both want the same thing.

If you want to make a really huge amount of money — hundreds of millions or even billions of dollars — it turns out to be very useful to work on what interests you the most. The reason is not the extra motivation you get from doing this, but that the way to make a really large amount of money is to start a startup, and working on what interests you is an excellent way to discover startup ideas.

Many if not most of the biggest startups began as projects the founders were doing for fun. Apple, Google, and Facebook all began that way. Why is this pattern so common? Because the best ideas tend to be such outliers that you’d overlook them if you were consciously looking for ways to make money. Whereas if you’re young and good at technology, your unconscious instincts about what would be interesting to work on are very well aligned with what needs to be built.

When you can’t decide which path to take, it’s almost always due to ignorance. In fact you’re usually suffering from three kinds of ignorance simultaneously: you don’t know what makes you happy, what the various kinds of work are really like, or how well you could do them.

Don’t wait. Don’t wait till the end of college to figure out what to work on. Don’t even wait for internships during college. You don’t necessarily need a job doing x in order to work on x; often you can just start doing it in some form yourself. And since figuring out what to work on is a problem that could take years to solve, the sooner you start, the better.

One useful trick for judging different kinds of work is to look at who your colleagues will be. You’ll become like whoever you work with. Do you want to become like these people?

The other thing you do in the face of uncertainty is to make choices that are uncertainty-proof. The less sure you are about what to do, the more important it is to choose options that give you more options in the future. I call this “staying upwind.” If you’re unsure whether to major in math or economics, for example, choose math; math is upwind of economics in the sense that it will be easier to switch later from math to economics than from economics to math.

Not everyone can do great work, or wants to. But if you do want to, the complicated question of whether or not to work on what interests you the most becomes simple. The answer is yes. The root of great work is a sort of ambitious curiosity, and you can’t manufacture that.