Well Im 41 and it does not get easier once you hit 40. Friends are tough to make. Have plenty of work acquaintances I chat with when im at work but no real "friends". Once you get out of school its just a lot tougher. People have their own careers / families and its tough to break through all that stuff.
Meetup groups do work well. Better then anything else I can think of right now. I play in a sports league which I have meant some cool people.