Suggest me a book that changed your life. No BS, genuinely changed your life

Hi guys,

I'm having one of those days where I feel quite dissatisfied with life. I need a book from your personal experience, fiction or non-fiction, that changed you. Genuinely shifted your perspective, philosophy, made you rethink everything, or ignited a passion in you.

I'm talking about a book where if you didn't discover it, you would be an ENTIRELY different person.