Inner Engineering: A Yogi's Guide to Joy by Sadhguru Jaggi Vasudev

To be fair to the book, it needs to be read first before undergoing the course of Inner Engineering offered by Sadhguru's Isha Foundation. In my case, I underwent the course first and then read the book and hence some parts of the book seemed repeated (as I had already watched the corresponding videos). In any case, a beautifully written prose with extreme fluidity and it is as if Sadhguru is talking and not as if you are reading a book. Some parts of the book are extremely invaluable like when he talks about the chakras, the Kundalini, rebirth, karma, etc. Definitely worth a read and a book to own.