Suggest me a book on gratitude (read the post body)

Hello,

I (m) am in my early 30s and I notice recently how negative I am. I grew up with a negative father who always had something bad to talk about people, and I came to the realization that I might have inherited part of that trait.

This is taking a toll on me. I am usually a nice person, but my negative thoughts and behavior have been overflowing and becoming visible in the way I treat people and live.

I would love books that can help me in my journey back to myself. My true self is a kind man, who loves people around him and giggles easily.

What books on gratitude you’d have to recommend me? Or books on “how not to be negative”?

Edit: if you could give me a brief explanation as to why you’re recommending that title or how that title helped you, I would appreciate it.