“Motion over emotion” is supposed to be a productivity aphorism, that suggests focusing on action and dedication instead of trying to rely on fickle motivation.
The phrase can also be applied to fiction writing. We should see the thoughts and feelings of characters in their actions, not by them being described.
It’s often distracting when the emotions of characters are described too directly or intensely; it’s more effective when the reader naturally arrives at their own interpretation of the characters’ inner states by seeing their actions.
Rather than being told that a character does something “gleefully”, we might instead see that they do it without hesitating in the scene, or they might comment on it to another character. Perhaps even better, we might assume they do it gleefully ourselves based on what we have seen this character do previously.
There must be a balance here between sparse storytelling that leaves the reader struggling to follow, and excessive control of the reader’s every thought as they read.