When do you know it's time to quit your job?

I decided this week that I need to start looking for a different part time job. After three years of working at the same job, I'm starting to realize things just aren't going to change. Even though it pays pretty well for a college student just trying to help pay the bills, there's got to be a better job out there for me.

You see, I work for a law firm where the work enviornment is very stressful. My job description list has grown longer and longer since I started. To sum it up, I do the amount of work that 3 full time people could do, only working part time. I'm tired and worn out. There are obviously more reasons than this but this is the biggest reason. I now realize I need a less stressful job while I'm going to school full time. I just hope that my next job will be more enjoyable and less stressful. I feel like doing something totally different like working at the OKC zoo...

What are some decent paying jobs for college students?