1. Languages - I started going to English meetups in my town to practice English; I found a group of like-minded people that I felt comfortable with and we started doing other things together - hiking, visiting castles and museums, drinking wine and talking till 2am.

2. Cycling - I love road cycling and there is a strong sense of community around cycling. If you are training alone and a bunch of faster cyclists catches you, you can draft behind them for a while and start chatting with them when you catch your breath; if you hit it off, you exchange contacts and start riding together. There are people that I have spent years and thousands of km with. The advantage of cycling is that there is a lot of endurance rides where you can easily talk and you get to know people pretty well.