Minimalism by Joshua Fields MillBurn & Ryan Nicodemus
This book and the approach has been gaining in popularity within a lot of circles of recent. I, myself have had this book on the pile for a couple of months, and I go it after I watched their documentary (https://vimeo.com/ondemand/minimalismfilm or found on Netflix).
The book is small and is around 120 pages long. I managed to complete this book within a few hours, and it's something that I will keep around. It describes the five areas in your life that you should declutter and gain more value from them.
The book provides many insights, and I believe it will have something which almost everyone can pick up from. If you want to better structure your life and focus actually on being happy, then read this book! Build a foundation for yourself.