I've always isolated myself, as a little tike and now as a middle-aged person. I don't have children, and I'm not close to my immediate family, emotionally or geographically. I don't subscribe to any dogmatic religion, so that hampers some possibilities.
I do have a lot of hobbies, but, I'm finding now that I need to get out.
I don't think going to gym will work for me, but I've toyed with the idea of taking a dance class. A little over a week ago, a creative soul I see sometimes on my cig break mentioned that she goes to the local Unitarian church. Several times a month they do a creative activity, other times environmental groups come in to inform us of local causes. It was a huge step for me, but I went two weeks ago for a get-together to make medicine bags. Though I wasn't all together confortable, it was nice to be doing something creative with other folks who weren't related to my workplace. I'm going to keep my eye open to other events that they might host.
I consider myself a "sociable loner" -- I agree with others' comments about quality over quantity.
Best to all.