One of the great books I am currently reading is Meditations* by Marcus Aurelius. This book reminds me time and again not to worry about things that I don't control and only focus on things that I can. This book introduces Stoic philosophy and I am surprised it is not that popular among Tech community (rarely being mentioned in Best Books HN posts).
*There are many translations of this book and the one I feel is easy to read is the one by Gregory Hays: https://www.amazon.com/Meditations-New-Translation-Marcus-Au...