15 Laws of Growth: https://www.amazon.com/15-Invaluable-Laws-Growth-Potential-e...
The Bhagavad Gita: https://www.amazon.com/Bhagavad-Easwarans-Classics-Indian-Sp...
The Four Agreements: https://www.amazon.com/Four-Agreements-Practical-Personal-Fr...
(Note: grew up Christan in rural Scotland now agnostic chilling in Manhattan, so no religious slants)
I see meditation coming up so frequently in discussions here, I wish some high karma person would post a "Ask HN: What's your personal meditation routine/journey, and what has it done for you?"
One thing to keep in mind is that there are lots and lots of different approaches to meditation. An approach that has been mostly de-religionized called "mindfulness meditation" has been very popular in the West in recent years, but there are many, many other methods too. Unfortunately, I know of no one comprehensive guide to all the different types. The information tends to be scattered all over the place.