I'm seconding what the others say. I see a few close friends 1-3 times a week in relatively unstructured or impulsive situations, and I also go to martial arts and latin dance clubs at no regular interval (although I should work on getting that back on a regular schedule), and play dungeons and dragons once a month. You can absolutely meet people with mutual interests in person, and it is worth pursuing regardless of whether you consider yourself an introvert or not.