1. It's not just that they don't pay you enough, it's that they couldn't ever pay you enough to make you feel good.
People who feel underpaid always think that more money will make them feel better. Sometimes it will, but sometimes it won't. And I can prove it. If your biggest complaint about your job is the salary, consider whether an amount 10 percent higher would make you happy. Then think of a number that is 20 percent higher. If a 10 to 20 percent increase would make you feel well compensated, you're in the right job—you just need to work on getting a raise. If you could go as high as 50 to 100 percent more and still not be satisfied, then money isn't the problem and more of it won't make you feel better. It's time to find another position within the company or a new job altogether.
2. You believe that nothing you do makes the least bit of difference..
This a demoralizing position to be in, but it's usually not the work itself that makes you feel as if you're not making a contribution. One of the world's most admired companies specializes in cleaning services, and its employees, who scrub office floors and bathrooms, believe they have reason to be proud of themselves and the work they do.
You need to discover a sense of purpose. Your job is making copies? Find out who needs them and why. Or maybe you need to shift your focus to what makes you happy outside of work—traveling, playing tennis, volunteering. Then you can think of your job as the means to make those activities possible. If you still think that everything you do is meaningless, then you need to prepare for a job change—because once you believe you're wasting your time, it won't be too long before your employer believes it, too.
3. You're not learning anything.
Of all the things that can go wrong with a job, I think feeling as if you're not growing is one of the most dangerous. The market for your talents is changing every day, and unless you are evolving, too, you run the risk of becoming as obsolete as punch cards in a software world. Be vigilant if you feel you are not learning anything and your current employer is paying you more than anyone else would. That means it is definitely time to run, not walk, toward opportunities for building new skills. (A boss looking to cut workers will always target the ones who cost him more than their talents warrant.)
You might register for technology courses or simply ask your current employer for new responsibilities. Concentrate on shoring up an area you feel is your biggest weakness or building on your second-greatest strength (you've probably automatically refined your strongest suit because it's something you love to do).