I used to hear this quite a bit from people who work here, as the article hints at we're a country of clubs and associations, most of them free. Be it chess, football, poetry slams, the church choir, the local CCC given that you're on HN, etc. Most unis will let you sit in for free as well. I also wouldn't worry about age. We're not really that age conscious, very few people I know care if they're around people twice their age.
People tend to bash their head in trying to make friends at work but it's probably the worst country to do this, we just work 9 to 5 and go home.