There is a song that includes the lines "I will learn to let go what I cannot change... but I will change whatever I can."
I think this is a good lesson for life. People always say "If you don't like something, change it." But that's not always possible. You change what you can and you learn to accept what you can't and work around it.
I have a coworker who is currently very stressed about a situation here at work. The situation affects our whole team, but this particular coworker is taking it very personally. It's causing her a great deal of stress, and she complains about it quite a bit. I understand her frustrations - but this is one of those things that we can't change. No amount of work or complaining or effort will have an ounce of difference.
My method of dealing with it was to vent for a few minutes, then shrug and move on. I can't change it. I have to deal with it. And I've learned to not let it bother me. On the other hand, I found out that it's causing her to lose sleep at night because she's so stressed.
There are things you can change and things you can't change. If you don't like your job, you can look for a new job. But that doesn't mean you will get a new job - the job market is tough. So you do what you can - you improve your skills and you look for a job and you try to find every option out there. But at some point, there isn't anymore you can do. So rather than stress, you just have to keep doing what you are doing and trust that it will all work out.
Sometimes you just have to learn to let go.