I found out a while back, and this is somewhat paradoxical, that if I care TOO much, I'm less happy. What happens is I notice all the stuff I can't fix, or need to fix, and other people get stressed out making them fix it. The end result is that I stop caring quite as much (I still care), get happy, and then start caring too much again.
It's especially hard at times when you have a lot of energy and want to make something work and you have to fight others who don't want to make it work. 8 hours plus of your day is a lot, so you want it to count, to matter, and that makes you care, to define yourself by that work, and that makes it hurt more. The alternative though, is just collecting the paycheck, which is also bad!
The trick is finding a balance and making sure you also define yourself by other things. And this is a very hard thing for creative folks to do, because it feels like their art, and it's easy to always want to hit the next target/goal/feature, in a never ending wave. The catch is they don't stop. It's a continuum. One of my first jobs as a kid was in a grocery store, and I learned clearing out the line was impossible, and the beeping doesn't stop. It is madness to want the beeping to stop because people from other lanes just come over to yours, and it won't.
I'm not great at this, but you just have to enjoy the people and the things along the way - as there's not a destination.