It took a long time for me as well. Kickboxing/crossfit didn't work. Volunteering at a local historic motor racing event every summer since 2010 didn't work (I like the guys, but they're acquaintances, not friends). It wasn't until I got hardcore into going to metal/rock concerts and festivals, and got into pen'n'paper roleplaying that it finally clicked for me, and I started making friends again.