Mistakes have been made

I'm going to try it.

First, let me preface this with something very important: you can treat all of this advice as SECOND-DRAFT ADVICE. It is so much easier to rewrite this kind of stuff once you have words on the page. Telling yourself the first draft is totally appropriate and acceptable.

What we’re talking about here are FILTER WORDS (and to some degree verbs of being). Yes, “thought” words are included. But so are “heard, saw, looked, tasted, smelled” etc.—most words having to do with the senses.

This isn’t black and white advice; sometimes you’ll use these words and that’s okay. They’re not WRONG. They’re just weaker. And they’re weaker because they create distance between the reader and the experience of the character.*

If you want your reader to feel like they’re experiencing the story right alongside the character, you want to cut down on filter words.

*This is particularly important with first person and close third POVs. The reader always knows whose eyes they’re seeing through and thoughts they’re privy to. So you don’t need to tell them “I saw X.” Or “I heard X.” Or “I thought Y.” You can just jump into the action/observation as it’s happening.

This is also where you want to pay attention to verbs of being.

you want to pay attention

to verbs of being.

That means that when you read a line like

John saw that the curtains were open.

It immediately takes you OUT of the character's perspective and instead tells you what they experience as a secondhand observation.

You don't have to get fancy or purple with how you rephrase things like this. Not everything needs a ton of breathing room.

You wanna know what's perfectly impactful while keeping a tight POV?

The curtains were open.

Some of this, yes, is about POV distance--but some of it is also about the information being conveyed by the sentence. If you are using a sentence like "John saw that the windows were open" it should be because the information you are seeking to convey is that John saw it.

Maybe this matters because the next time John looks back they are closed, and so he's doubting what he saw. Maybe it matters because he later has to recount information about the room he was in, and it's notable that he specifically saw that the windows were open. The fact and method of his observation is part of the point of the sentence, rather than simply the observation itself.

When we are using sense verbs, it should be because part of the point is the sense. Same with "thought", "felt", etc.: "Mary thought that Susan looked a little thin" is telling us a different piece of information than "Susan looked a little thin."

Contrarily, at least in my opinion, simple telling phrasing like "It was rainy" can sometimes bring us more into a character's head than something showing like "The rain howled like an injured animal." I have read books when a relatively plain-spoken/plain-thinking character suddenly starts having elaborate descriptions of things like scenery or weather, and it is abundantly clear that the author wanted to spruce up their writing and avoid "telling." The problem is that it drags me as the reader out of the character's head and shows me where all of the strings are. I'm suddenly thinking about how the author is worried about being yelled at for "telling" instead of just reading the story.

IT LITERALLY MEANS "HEED THE TAGS" "YOU HAVE BEEN WARNED" IT'S LITERALLY MEANINGLESS WITHOUT ANY FURTHER TAGS OR WARNINGS

YOU'VE JUST SAID "BE WARNED" TO ME AND THEN LEFT WITHOUT ELABORATING

And what is the purpose of placing a flag on a foreign planet? It’s a way to say “we were here.” And the one, immediate symbol that any other human who came to the same spot any number of years later would be able to recognize a human hand. Even if governments change and collapse, we all understand a handprint.