Fall in love with some activity, and do it! Nobody ever figures out what life is all about, and it doesn't matter. Explore the world. Nearly everything is really interesting if you go into it deeply enough. Work as hard and as much as you want to on the things you like to do the best. Don't think about what you want to be, but what you want to do.
— Richard P. Feynman, in the collection Perfectly Reasonable Deviations from the Beaten Track: The Letters of Richard P. Feynman (edited by his daughter Michelle Feynman)