If we're going meta, I'd add Ecclesiastes (yes, from the Bible). Doesn't matter whether you're religious--this was also a favorite of noted atheist Christopher Hitchens, for example.

The basic theme is that everything is ephemeral. This really starts to resonate when you see how fast the results of your labors over a period of decades fade, turn to dust, and are utterly forgotten. As you yourself will be in short order. Ultimate medicine for keeping things in perspective.

Here's a particularly readable paraphrase: https://www.amazon.com/Nothing-New-Under-Sun-Ecclesiastes/dp...