Every story has a rhythm. If it’s a monotonous one, readers may lose interest. Pacing the rhythm can build tension, emphasize important events, stir the reader’s emotions, and move the action forward. As the story progresses, the tension builds with each new conflict, and ebbs slightly as minor conflicts are resolved. As the climax approaches, the tension increases.
Proper pacing will keep the reader moving forward but allows the action to slow down when appropriate to emphasize the importance of certain things along the way.
To increase the pace:
Use shorter paragraphs, shorter sentences, and occasional sentence fragments.
Use less description, more dialogue.
Use active verbs and fewer modifiers (adjectives and adverbs).
Focus on the events that move the action forward rather than switching to subplots.
Have something important happen in each chapter, and keep the chapters short.
Cover periods of inaction with a transitional sentence rather than going into details about what happened.
To slow the pace:
Use longer sentences, longer paragraphs.
Include more narrative and less dialogue.
Use more modifiers, less active verbs, and passive sentence structure.
Switch to subplots between chapters high in tension.
Layer in significant details to emphasize their importance (foreshadowing) .
The type of story will dictate the appropriate pace. For example, a mystery will generally have more action and a faster pace than a romance. But every story needs a rhythm that keeps the reader interested enough to keep turning the pages. Pacing sets the rhythm.