Whats a good non-college based Fraternity to join?

I went to a private college with no Greek life. I just graduated and am looking to join a fraternity, but the only problem is most are a part of a college. Since I don't go to college anymore I can't join. I looked at groups like Kiwanis and Lions club but they are all old guys. I am 23 so it would be nice to join a group of similar aged guys. I live in Tampa if that helps at all.