This summer I went through a transformative (read: difficult) experience, which caused me to grow immensely. Thus, to help my self-diagnosed depression, I read The Power of Intention by Dr. Wayne Dyer and also The Power of Now by Ekhart Tolle. I recommend reading them in that order as the former book has beautifully illustrated pages in full color and it’s a lighter read than the latter.
The main premise of Dr. Dyer’s book is to keep connected with your higher self (you know, the good, kind and ego-less person within you) by not allowing negative thoughts to linger in your mind (and therefore become strong) and to focus on cultivating positive thoughts. The Power of Now is also about keeping connected to your higher self but through a constant reiteration of being in the present moment while elaborating on exactly what that means from many different angles.
I truly believe that we are what we take in (not just through food, but also thoughts, sounds and images) and these books have certainly helped me stay better connected to my higher self through this reinforcement. And with the higher self comes the ability to understand others (because in the macrocosm we are all one) and where they are on the path to finding the good within themselves. This is wisdom.