This month I have chosen Why Has Nobody Told Me This Before? by Dr. Julie Smith. 
If I were to write my own book on the best mental health tips and important things to know, it would have basically been this book.
She does a great job at concisely explaining a lot of really important information in easy-to-understand language.
She reviews a lot of important cognitive behavioral therapy principles and also incorporates other holistic information. This is my new go-to recommendation for if you were stranded on a desert island and could only bring one book related to mental health. Check it out soon.