I need to stop making assumptions about people and just chill

I’m always stressing and assuming the worst about what people I like are doing that I don’t know about, what they think of me, what I’m missing out on. I need to chill the fuck out. Like I was right after high school, nothing fazed me. Need to be like that again. No one likes a holier than thou paranoid asshole. Basically I need to start being more comfortable in my own skin, letting things be, and stop caring so much about other people.