Serendipity is "the act of finding something valuable or delightful when you are not looking for it." Bask in everyday wonders keep your eyes open or you'll miss them.
Happiness isn't having what you want, but rather wanting what you have. That may sound cliché but it's a truth. And the happiest person of all is the person who realizes they have what they want right in that moment. They realize that the time they're living in is that treasured moment worth living. The couple who knows they're happy when they have each other is the happiest couple to behold. They know how to use each of the six principles outlined in this book and they could probably expand on each one.