If you're 10–20: These are prime years!

Make things. Operating in a space with a lot of uncertainty is a very different experience to learning something.

Make friends over the internet with people who are great at things you're interested in. The internet is one of the biggest advantages you have over prior generations. Leverage it.

practice coming up with your own worldview.

One of the main things you should try to achieve by age 20 is some sense for which kinds of things you enjoy doing. This probably won't change a lot throughout your life and so you should try to discover the shape of that space as quickly as you can.

To the extent that you enjoy working hard, do.

If you think something is important but people older than you don't hold it in high regard, there's a reasonable chance that you're right and they're wrong.

If you're 20–30: I don't know yet. I plan to think about this when I'm 35-40.