I didn’t write a book, so I can’t answer your question 😀
Hearing the word happiness, philosopher Slavoj Zizek always comes to mind. Here’s a quote:
“Happiness was never important. The problem is that we don’t know what we really want. What makes us happy is not to get what we want. But to dream about it. Happiness is for opportunists. So I think that the only life of deep satisfaction is a life of eternal struggle, especially struggle with oneself. If you want to remain happy, just remain stupid. Authentic masters are never happy; happiness is a category of slaves.”
Haha, that sounds a bit crude. Here’s a video with some more nuance:
Just to get you to think about hapiness.