I LOVE self help books!
The Happiness Project by Gretchen Ruben is one of my favorites. She doesn't give advice, she just takes it (all of it!) and then processes what works for her and what she learns about herself from it. When I read it, it really got me thinking about a lot of little ways to be more intentional about being happy.
One Thousand Gifts by Ann Voskamp is about cultivating gratitude and is only $2.99 for Kindle.
I've just started reading some of
Brene Brown's books, and her research on shame & vulnerability and whole hearted living are really powerful.