My favorite book of the moment is this title from Chronicle Books. The book is the work of Susan O'Malley, an artist who passed away in 2015, but not before asking tons of people of all ages what advice they would give themselves if they could meet themselves at 80.
The question is a heavy one, often forcing people to look deep into themselves and their decisions. The question has this sort of redeeming, uplifting quality to it, able to lift people out of bad times and make them see how good everything is -- even when it seems really bad.
Her work in transforming these small quotes into colorful, vibrant posters makes this book just a pleasure to look at and read. I highly recommend picking up a copy and keeping it near you.