I met my wife at a semi-organized fun run.
Actually it was at an informal meal gathering after the run.
We have been together a long time.
My advice: get out there and do things you like to do. You are not going to meet anyone in the basement. Be friendly, open, and a good person and people will respond to you.
Do not go into situations with expectations or just because you think you will meet someone there. Do what you like to do because you like to do it. By keeping it real you can meet someone who has one of the same interests as you. (something in common).
If you really like to hang out in bars and drink, go do that, but you are likely to meet other people who like to hang out in bars and drink there.
We had both traveled some miles to attend the fun run we met at. We both went out there, a little beyond our comfort zone and normal haunts, to be there. And we both would have been happy with the experience even if we had not met each other.