The Enchiridion of Epictetus is a compilation of 51 tips on how to live a happy life based on stoic ideas. Here are two of the tips:
Upon every accident, remember to turn toward yourself and inquire what faculty you have for its use. If you encounter a handsome person, you will find continence the faculty needed; if pain, then fortitude; if reviling, then patience. And when thus habituated, the phenomena of existence will not overwhelm you.
It’s hard work but I can’t think of a faster way of improving your character.
Let death and exile, and all other things which appear terrible, be daily before your eyes, but death chiefly; and you will never entertain an abject thought, nor too eagerly covet anything.
First-world problems and their associated emotional impact become largely irrelevant with exercises like this.
The advice is highly practical and after several weeks of applying some of the tips I can say my inner peace is increasing. I find it telling that the most useful advice I’ve come across lately comes from people dead for millennia.
If you don’t have enough with The Enchiridion check out Meditations by Marcus Aurelius.