I know some people will recommend those self-help books. The author usually spend multiple chapters explaining why and how you should follow your dream. The problem with that is you won’t be motivated by reasons.
I will recommend whoever want to follow their dream should read the biography of their idols. Take myself as an example, I love basketball and I like Michael Jordan. I read his book Michael Jordan: The life and found that very motivating. I guess the reason is because an idol by definition, is someone you want to follow.