So a large percent of people have a crappy job and work with crappy people and have crappy bosses. The last century of management still hasn't solved that issue, so it's likely going to be an issue for the next century.
I ask myself these questions:
1. Do I have a life outside of work? "Yes" is a good thing. But "No" is not a deal breaker.
2. Is my identity of myself too entwined in the corporation? If "yes" it's time to do things entirely unrelated to work. They're paying me to do work, not sit around and stew how unfair they're treating me after all the loyalty I've shown them.
3. Are the people there decent human beings that don't know how to manage, or are they back stabbing assholes?
The former is far more forgivable than the latter. Once the culture of back-stabbing starts, you're not gong to fix it ever.
4. Are the hours you're working actually making a difference? IOW have you been told to work 60 hours a week on a project that got canceled? This one is rough, because you're not getting those hours back, nor are you going to get to get a bonus for working hard on a canceled project. At what point did it become clear things weren't working?
5. What does my job enable me to do that I couldn't do without it? Expensive hobbies or travel?
6. Is work/life balance a two way street? "Yes" awesome. Again a "No" is not necessarily a deal breaker. Many people have jobs they need to be on call for or stay late for.
7. Am I growing? Am I learning how to deal with difficult people? Or is this a wasted amount of energy?
8. How long does it take me to reset from "anger" and "frustration" to calm and productive? If I can't leave in the evening and forget about work then something's wrong.