When you were younger you probably made friends because you were all in school/college/university together. Some people make friends at work for the same reason (I've never really understood this though. After seeing them for 8 hours or so the last thing I want to do is spend time with them outside of work.) Where else can you go where people are gathered where friendships are likely to be created? Church/mosque/synagoge/temple/etc. was the typical answer for thousands of years. Maybe a service club like Kiwanis, Lions, Rotary? Though I typically think of those belonging to those kinds of clubs as being old men. Maybe there is somewhere else you could volunteer where you might meet like-minded people?