One how-to writing book I read recently emphasized manipulating readers' emotions. I hate to say it, but emotions grab readers.
How's a poor author supposed to manipulate a reader's emotions? By making the characters feel emotions. When people read fiction they become the characters they read about. If the protagonist is emotional, the reader will be more likely to be emotional and will be more likely to be grabbed by the story.
Unfortunately, you can't have emotions for no reason; they need to be integral into the story. This is done by having high stakes. The situation the protagonist is in needs to be important.
The good news is we all know at least one person very, very well and we can mine that knowledge for our fiction. What's the worst thing that could happen to you? What would rock you to your core? How would that make you feel? Why? What would be the consequences? What would you do to resolve or fix that? The deeper you delve into your psyche, the more writing seems like therapy--but maybe that's a good thing. Ultimately, readers want truth and understanding about the human condition.