Read these modern philosophy books for happiness

Early Retirement Extreme - Jacob Lund Fisker. I mean I consider this a modern philosophy of life. Philosophy is meant to answer the yearning of the soul.

Your Money or Your Life - classic book. Introduces the concept of trading life hours for what. The practice of tracking every single expenditure. The idea that your hourly rate should also include commute and shopping for appropriate work wear.

Rich Dad, Poor Dad - the idea using debt, purchasing assets instead of goods, appreciating instead of depreciating things. all in all, you can skip it. it is worth just a blog post, and the content is covered more succintly in Early Retirement Extreme.