Think about the book you are writing. Think about the book you want to write. Picture it in your mind, the characters, the setting, the themes, the mood. Is it gritty? Is it lush? Is it joyful? Find yourself in that place, that world, surrounded by those characters. Now, answer this question in one sentence.
External conflict on its own rarely stands up as being big enough, emotional enough or important enough. Yes, external factors are important in keeping a story moving, but internal factors are the driving force behind character arc and development, and our pathways to making two-dimensional, imaginary characters human. Real.