By Sam Harris
In this book, Harris makes a case for spiritual practice without the scaffolding and foundation of religious beliefs. While he approaches it as an avowed and enthusiastic atheist, I think that the core insight that there are certain practices you can adopt to bring peace, contentment, and compassion into your life without adopting beliefs you are uncomfortable with is useful regardless of your religious convictions. The descriptions of what it feels like to meditate and what it feels like to think you're meditating when you aren't really are worth the price of admission by themselves.
Buy it here.