How do I stop thinking about how people perceive me

I'm always thinking about the things that I've done to other people, and how they perceive me after it. It's very draining, trying to fit in.

Constantly conscious of what people say to me, thinking about why they said that if they don't like me or what not. i need this to stop, because I didn't care about how people saw me as back then. Now it's just a normal occurence. Any thoughts?