The title of your post is a great question, an interesting one to consider.

I think that for me, these two things, the way I think about an event that is more or less upsetting to me and my mood, seem to mutually influence the other.

A while back I started noticing how "even" I felt all the time. I told my T, maybe it's a delightful apathy. But I'm not an apathetic person in any way and I don't think anyone would characterize me or the way I am in the world as that.

Instead, I think it was just that I'd become less attached to my moods, less concerned about whether they were up or down or sideways or whatever. And I noticed that the things that happened that were not joyful or pleasant were just not that big a deal at all. And as I started to think more that the bumps in the road with my wife or children or friends were just not that big a deal, my mood stayed pleasantly unflustered. And then people in general just seemed less hostile and more kind. Maybe emotions and cognitions are a vicious circle when things go bad and an uplifting spiral when they are going well. Maybe they emphasize the negativity of each other, but they can also promote their collective positivity.