How do I stop caring what people think?
You stop caring what people think by noticing that you were never actually reading their minds, you were running a private simulation of their judgment and reacting to the simulation. The fix is not to build thicker skin. It is to catch yourself mid-simulation and ask whether the person in question has spent even ten seconds thinking about you today.
The audience in your head is not real
When you replay a conversation and cringe, you are not remembering what someone said, you are remembering the face you imagined them making. Most people you worry about were checking their phone, thinking about their own bad day, or already forgot the moment you are still narrating. Psychologists call the gap between how much attention you think you got and how much you actually got the spotlight effect, and it is not a mild bias, it is often off by a factor of ten. You built a jury out of people who never convened.
This is not a flaw, it is a leftover alarm system
Caring what the group thinks kept your ancestors fed and alive, exile from the tribe was a survival threat, not a social one. Your nervous system still treats a raised eyebrow like a potential eviction notice, which is why a single skeptical text can wreck your whole afternoon. The wiring is old and it does not know that a coworker's silence in a Slack thread is not the same as being cast out of the only group of humans for two hundred miles. Knowing this does not delete the alarm, but it explains why the feeling is so disproportionate to the actual stakes.
What actually shrinks it
Make the list of people whose opinion is allowed to cost you sleep, and keep it short on purpose, five or six names, not a category like everyone at work. When a stray judgment lands, ask specifically whether it came from someone on that list. If your manager said your report was thin, that is real information and worth sitting with. If a person you met once at a conference seemed unimpressed, that is a guess you made about a face you saw for four seconds, and guesses are not verdicts. The relief comes from sorting, not from pretending you feel nothing.
Watch what you do right after the sting
The moment right after you feel judged is where the pattern either repeats or breaks. Most people either replay the moment on a loop, seeking a rewind, or perform overcorrection, becoming louder or more agreeable to smooth it over. Both respond to the imagined verdict rather than to what actually happened. A better move is a single flat question: what would I do next if I had already decided this person's opinion carries no vote. Then do that thing. The caring quiets down once your behavior stops waiting for a verdict that was never coming.
When this runs your life, it usually traces to one underlying pattern. For this, it is most often the Mirror rhythm, the thing under the behavior.