
I'm going to echo a lot of what Virella said. By and large, people keep their characters' internal thoughts to themselves since others can't just read their minds and know what they're thinking. It's much better to, as Virella mentioned, use your character's actions to show how the character is feeling, rather than just telling.
This could be as simple as using -ly adverbs, but sometimes I do find myself clarifying or summarizing a character's disposition when it's the result of multiple motions or expressions (e.g. "John folded his arms and gave Jane a flat stare, clearly not believing her." "Lara sat quietly and got a distant look in her eyes, the gears in her head clearly turning as she processed the information.") I also usually just say something along the lines of "gave such-and-such an incredulous look" instead of going through the long form of all the different visual cues (motion in the eyebrows, staring, leaning in a bit, maybe a slightly slack jaw) that would create that effect. Sometimes, I'll have one, maybe two of those cues, but never the whole shebang.
Outright using thought like internal speech, however, isn't very fruitful, as no one else can hear you think and they have no way of reacting to it. At best, people might view it as a flowery and unnecessary addition in a medium that's usually concerned with space constraints, and at worst, you're opening the door for someone to magically know things they shouldn't or running the risk of someone forgetting two months down the line that you only thought that super incriminating thing about yourself and didn't say it. Any internal thoughts you write essentially become OOC knowledge that needs to be kept separate from what the characters know, and they come with all the same baggage.
Anyway, that got a little soap box-y, but I hope that helps!
This could be as simple as using -ly adverbs, but sometimes I do find myself clarifying or summarizing a character's disposition when it's the result of multiple motions or expressions (e.g. "John folded his arms and gave Jane a flat stare, clearly not believing her." "Lara sat quietly and got a distant look in her eyes, the gears in her head clearly turning as she processed the information.") I also usually just say something along the lines of "gave such-and-such an incredulous look" instead of going through the long form of all the different visual cues (motion in the eyebrows, staring, leaning in a bit, maybe a slightly slack jaw) that would create that effect. Sometimes, I'll have one, maybe two of those cues, but never the whole shebang.
Outright using thought like internal speech, however, isn't very fruitful, as no one else can hear you think and they have no way of reacting to it. At best, people might view it as a flowery and unnecessary addition in a medium that's usually concerned with space constraints, and at worst, you're opening the door for someone to magically know things they shouldn't or running the risk of someone forgetting two months down the line that you only thought that super incriminating thing about yourself and didn't say it. Any internal thoughts you write essentially become OOC knowledge that needs to be kept separate from what the characters know, and they come with all the same baggage.
Anyway, that got a little soap box-y, but I hope that helps!