I know this is a really old post & I haven’t read this entire thread, but I never miss a chance to recommend this book - The Power of Now (by Eckhart Tolle)
The book completely changed my life. Basically teaches you how to stay in the now, control emotions, understand others, meditation. I read it so many times I have a lot of it memorized. My brother was going thru a hard time, he was lost (going thru opiate withdrawal, which can really mess with the mind) & we would talk for hours, basically me reciting the book & him asking questions…it changed his life too. In an extreme way. He used to be extremely irritable, extreme anger issues, short temper, just bad. He is a COMPLETELY different person now. They call him preacher at work (it changed his life so much & brought him so much peace & happiness he wants to spread it everywhere he goes now).
It’s an amazing book & I think there is a free pdf version online. If you are not religious do not get scared off by the god talk. He discusses god in a different way & no matter what your beliefs are, there’s just so much good stuff in this book.