Another factor that is important is being open-minded, whether that means being a little more willing to explore things that aren’t your wheelhouse or being tolerant of behaviors or lines of thinking that aren’t natural to you. That doesn’t mean you need to pretend to be someone you loathe or surround yourself with insufferable people, but instead find a way to deal with averse concepts in a constructive way, to be just flexible enough to find an enjoyable common ground. Walk away if there isn’t any, or it isn’t worth the effort you have to put in.
I think too many people think friendship is what happens between people that are the same, and it happens magically and effortlessly. Friendship is work, always. Some people are just less work or pay higher dividends than others. You need patience and the ability to know when a friendship costs more than it’s worth. I think we just tend to have less patience, energy, and flexibility as we get older, but some of that is a choice.