I have to do blood lab work pretty frequently, and it always makes me exhausted, many times I pass out. Today I thought about how poorly I would do if I were, say, a fantasy character who was injured in a battle and lost blood. And add on top of that the "energy" being used to do magic, too. But seeing a character say "uh oh I had one bad wound, I gotta sit down for a bit" isn't very exciting, so I'm just gonna...ignore that. But in the fantasy genre there is a bit of wiggle room as to how much abuse someone can take in a fight before they can't go any more, so that's not too crazy.
Have you ever shot a gun? Do you know what the kickback feels like? Or how LOUD it is? So, SO many pieces of media just...ignore that guns are really loud. If you fire a gun without ear protection, you're going to have problems. You won't be able to talk to someone, for one, and tinnitus really affects your ability to navigate/do things in ways you don't really realize until you end up in that situation. But it would be not very exciting if your character can't understand what anyone is saying to them after a gunfight (though the use gun/explosion-caused tinnitus as a running joke in Archer). We all just sorta accept that guns in tv/movies/books/video games don't act the way they do in real life to make the story work better.
If you're familiar with the tropes and conventions of the genre you write, the more you'll get a feeling of what is in the normal realm of possibilities and what would be too out there.