suggest a book about learning to be alone and not craving validation from others

hi! so I've come to realize that I'm a people pleaser. I care a lot about what people think of me so I refrain from voicing my opinions and interests. I want to stop doing this, even if it means having no friends at all. I want to stop caring so much about what people think of me. I want to learn to enjoy my own company.

I've found that books more than anything have helped me internalize messages in the past. So, please recommend something that you think might help! It could be fiction, philosophy, psychology, anything! It'd be nice if it wasn't super dense or long.

thanks!