My advice would be to make an effort to participate in group activities if you don’t already. Try to open up to a few people and see where that goes. For example, I started going to a run club last summer where we run at least once every week, and I continue to meet interesting people each time. Stay a little bit after the run to socialize. A lot of them it turns out joined so they can socialize and motivate themselves to be more active, just like me. You can start at your own pace, even walk if you need to, of you’re not a runner per se. We had a special holiday run last week where we celebrated afterwards with lots of games and activities at a bar/video game arcade and it was a blast. An added bonus is that now you’ll have fun social activities to talk about when you meet new people outside of the club. I’ve met people that are into board games, cycling, you name it. So that opens up new doors for other types of activities. It gets easier after you start going regularly and everyone recognizes you. Starting a conversation is as simple as asking how their day/run/whatever went.