Stealing Fire dives into altered mental states through psychedelics and sex, to extreme sports and Navy SEALs training. It was published recently (Feb 2017), and is highly rated everywhere. Definitely a must read.
Among the top books this year so far. Great subject matter, writing style, and flow. If you seek to open your mind and challenge your existing frames of reference, I highly recommend this book. And perhaps, daily meditation, and quarterly psilocybin mushrooms.