Maass gets his students to go deeper into the story by having us ask questions of ourselves and our characters and our stories. Here are a few examples:
What is your protagonist's bad habit, weakness, vulnerability, blind spot, etc? When does this embarrass your protagonist? Who notices? How does your protagonist react?
What is something your protagonist never told anyone? What was your protagonist's worst mistake? Who would your protagonist most not want to let down? Who would be most disappointed in your protagonist? Would knowing the truth be a devastating blow or a revelation?
Immerse the reader in characters' feelings. Try doing an "emotion draft" and ask what is the strongest emotion of the POV character in this scene, in the next one, etc. What's right about this feeling? What's wrong? What are the secondary emotions? What feeling is the POV character avoiding? All of this creates a fresh emotional experience for the reader.
How can we approach feelings in a way that feels FRESH? Obvious emotions are not needed on the page. It's the secondary ones that bring something different to the page.
But it's not enough to just put emotions on the page. Use them to create conflict inside the character. Counter expectations, push the reader off balance just a little. We can create uncertainty and move the story forward just as much with emotions as we can with high action.