“Show it, don’t tell” is a good rule of writing. The basic idea, for those who don’t know, is that instead of telling me a character is grumpy, you should instead show me through their actions. In other words, don’t give me pages of exposition from the narrator, but show me through the plot development. That rule is even more true in visual media like comics, but of course, we’re still prone to this pitfall. Note just about any film that features heavy narration telling us what the lead character is feeling about a particular turn of events.
BEARD: They're like sharks--if they ever stop moving they'll die.
BEARD: Well, I do teach my creative writing students to "Show it, don't tell".