Sam Altman’s advice for 19 year olds:

No matter what you choose, build stuff and be around smart people. “Stuff” can be a lot of different things—open source projects outside of class, a startup, a new sales process at a company you work at—but, obviously, sitting around talking with your friends about how you guys really should build a website together does not count.

The best people always seem to be building stuff and hanging around smart people, so if you have to decide between several options, this may be a good filter.

Working on something good will pull you along a path where good things keep happening to you.