They spent every waking moment dreaming first and later working to make those dreams come true. Kids get this. They don’t question if their dreams are crazy. It’s just a natural creative process. It’s the grown-up world that tells the kid to “grow up” or “be more practical” or “that’s impossible!”
Just think of how many love ballads you can write with the famous quote of “Offer them something they can’t refuse” from the Mafia movie, The Godfather! Totally unrelated yet can easily turn it into at least 5 or 6 great songs. And this is even much easier to do with the romantic movies. Just keep watching and keep your ears sharp for catching some awesome lines from the classic movies.