I think I understand, Joan. Somehow, somewhere along the line, some of us become designated as "fixers." And we buy into that, accept the responsibility, and go about the rest of our lives noting the things that are out of whack and setting about to fix them - put them right - take care of it - tend to business.
My dad didn't abuse my mom when I was present, so I learned very early that my job was to AlWays be there, to protect. My husband couldn't get along with his birth family, so I was the designated intermediary. The garbage disposal quits and nobody volunteers to check it, so it's my hand down in there with the gunk and blades; or it's me, upside down and backwards, under the sink looking for the reset button. etc, etc, etc
I'm not sure this is an appropriate response about the ability to focus on the good stuff, but I do know that when something needs attention, there are those of us who respond - and there is enough bad stuff out there ... we don't get around to the good. We are consumed. Swallowed up. Drowning. And nobody even notices. We see the hurts, the inadequacies, the problems, the injustice, and dive in to make things better. Doesn't mean we don't appreciate the good outcomes, just means we're busy tending to things that othes don't want to, can't, or refuse.
Eventually we get tired, then depressed. How do we unlearn one role and learn a new one? How do we focus on the nice things while other things simmer and boil? Danged if I know!