The title of the book is a bit misleading. This book is not about not giving a f*ck at all, but rather about being selective about the f*cks you give. It reads a bit like a stand-up piece on the art of saying no, accepting the temporary nature of your existence and enforcing your core values with your behaviour.
It combines personal anecdotes with snippets of stoic teachings, zen buddhism and psychology. It’s a very gentle introduction to taking up responsibility for who you are and who you want to become. If it feels too light and “fun”, it is because it is. For a deeper lecture, refer to some of the books mentioned in here. “The Denial of Death” by Ernest Becker or “Mediations” by Marcus Aurelius are both recommended for a deep dive.
I totally recommend it if you haven’t read anything remotely similar before or you want to be mildly entertained. But if you are familiar with the concepts mentioned, you can safely move along to more comprehensive readings on the subject.