Radio Shangri-La: What I learned in Bhutan. the Happiest Kingdom on Earth by Lisa Napoli. Just came out in February.
Read up to the end of chapter 2 before bed. Love it so far! And I feel like I can totally relate (not that I'm 40 or burned out or overwhelmed by regret... but I am looking for a way to recharge my life).
I'm fascinated by the idea of National Gross Happiness. Sounds like a wonderful way to live! Looking forward to learning more about Bhutan and their way of life.