I like action in my entertainment. Books, movies, TV shows, even games. I enjoy a great story to go with it, but I want to see people in peril more than I want to see them examining their lives in a safe environment. I like the external forces that cause the true nature of a person to bubble to the surface. I want to see what people do. As you might guess, I write a lot of action scenes in my books.
At this point, action comes pretty easily to me, but that wasn't always the case. My early work was way too descriptive in how my fight scenes played out -- every detail explained, special names created for styles and whatnot. It took longer to read the action that it did to actually perform the action.
Action can be tough because it's easy to focus too much on the action and not enough on the character in peril. So long descriptions sneak in and what the character does takes center stage. What the character thinks and feels often gets shoved into the background.
And that's bad. Because those emotions are what make or break an action scene.
Get in Their Heads
I try not to let too many straight descriptive paragraphs go by without hearing from my POV character in some way. A line of dialog, some internalization, something that puts the reader back inside the POV's head. Readers care about the characters. They want to know how the characters feel about what's happening to them. They want to know what those characters are going to do next. Without that connection, the action is just details on a page.
From a purely structural standpoint, it also helps break up the text so you can better control the pacing. Description slows down the narrative. Dialog speeds up the narrative. Long chunks of text encourages skimming by the reader, especially if it's an exciting action sequence and they're eager to see how it turns out. But when readers skim, they stop on the dialog (spoken or internalized), because that's usually where characters make decisions. So breaking up the scene visually helps keep the reader reading and not jumping to the next set of dialog lines.
Make it Personal
Stakes are critical to an action scene. If the reader doesn't care, there will be no excitement. Think about those summer blockbuster action flicks where there was a ton of action, but you just kinda sat there and waited for it to be over, even though it was cool to see. Was there ever any fear that things wouldn't turn out fine for the hero? Was the outcome ever in doubt? You don't want to do the literary equivalent. Making sure your stakes are high and personal to your protag will help prevent that.
Stakes also help make whatever the problem is larger than life, because it matters to your protagonist. The opening of The Shifter works because readers care about Nya getting her breakfast. But all she's doing is trying to steal a few eggs. It's not earth-shattering, the world won't end, it won't even matter to anyone else but Nya. But that's the key. To her, it's a huge deal. It has major repercussions. And if readers like her, they'll care about how this problem turns out.
Add a Surprise or Revelation
Not every scene is going to lend itself to this, but the thing that keeps readers reading is the desire to know what happens next. If your action scene is one of those where the outcome really isn't in question, but it's a vital scene to the plot (and these are pretty common), add something to it so the reader gets information they weren't expecting. Share a secret, show a talent the character hadn't yet revealed, discover something that affects the plot. Give them an informational reward for watching your action scene. Discovering there are treasures in those scenes will also encourage them to read every word, because they'll never know what vital clue might be found.
Pacing is almost as critical to action scenes as stakes. The goal is to get the reader caught up in the action, heart beating, breath racing, turning the pages as fast as possible. Short sentences add speed. They create excitement. Long sentences slow things down and lessen the excitement. Action scenes are typically not where you're going to go into long descriptive passages or deep thoughts. (unless you're purposefully giving the reader a breather)
Narrative flow matters more here than probably anywhere else, because if you write something that trips up the reader, you pull them out of the story. You want your text to flow as smoothly as possible so it sucks in the reader and whisks then along like a leaf on the wind. So watch out for choppy sentences, which are common when you write action and are trying to keep this fast-paced. Keep an eye on your sentence structures and the rhythm of your words. Keep them varied, keep them moving.Read the scene out loud. There's no better way to catch bad narrative flow then to hear it spoken.
A good scene is all about events unfolding that the reader wants to see a resolution to. If you treat every scene like an action scene, there's a good chance you'll keep a tight hold on your reader and they won't be able to get away.