But I'd start with trying to be sociable, to make friends. Try hard to not be extremely picky about the kind of groups you hang out with. Do social things (join choirs, join groups that do pick-up sports, join dance groups). All face-to-face, not online.
That's very practical, thanks for your suggestions. Some people are more extrovert and *charge their batteries by being with others. Other people are less extrovert and thus somehow consume their energy when they happen to be in social situations.
I always thought to be one of the second kind, but as time went by I started to consider myself less introvert than I expected. Thanks again for the suggestions.