I picked up this book on a recommendation from Ramit Sethi. Central thesis: (insert here) Overall the most useful concept for me was the one of energy being oscillatory. Take a moment to consider how broad a range of emotional muscles you have in your own life. In all liklihood you will discover that you have considerably more strength on one side of the spectrum than the other. Notice, too, the judgment that you bring to the relative merits of opposing qualities.