Comes with self-confidence. You just have to tell yourself that humans are frail, everyone has their weaknesses, and probably variations of the same insecurities you have.
The main differences are the masks they put on and the roles they play.
Develop a good act, and fake it. It'll feel awkward at first, but soon it'll be natural.
@WoodyAq Thanks for the advice! I made progress during the past years, now I manage to talk to people and don't worry about looking weird/ridiculous, but sometimes after having a conversation I start shaking all over, get a headache bla bla. Like I feel now.