Do you enjoy writing action scenes? I know I do. It's exciting to get one's characters moving and conquering their obstacles, defeating their demons, whatever it takes to achieve their goals. However, as they struggle or battle their way along, don't forget to bring their thoughts along with them. After all, they are human and you need to let your readers see this. If you don't include those inner thoughts and reactions of your characters, they will seem mechanical and robotic. These emotions can be external, visible reactions to a situation or internal thoughts, unseen emotions.
The ability to successfully balance the mixture of outer action and inner reaction takes practice. Study your favorite authors' works and see if you can pick out the use of action and reaction of the characters, how well they blend the two components. Now, mentally remove all the inner thoughts/reaction of one of those characters and see how much of a difference it makes. More than likely, you will be left with a mechanical, robotic shell of that character. And finally, take note of your own writing. See if you can identify where you used reaction along with your action. Then, let me know what you discover. Hopefully, it will be great news!