How do you know when it's time to quit your job? I've left jobs before, whether it was because it was time for me to do something else or because it was due to a "mutual agreement to move in separate directions." But how do you know if you've stayed too long in a less-than-ideal situation?

Here are the tell-tale signs, according to Jeanne Sahadi.

* You have a lot on your mind, not just work. Other possible things on your mind: any one of the various websites you maintain, or, blogging on any one (or more) of the websites.

* Things change, not to your advantage. For example, your department personnel shifts majorly but you're not immediately promoted and given more responsibility.

* Your boss takes you for granted. Perhaps "Good job!" and occasional high-fives are not enough to make you feel appreciated.

* You pigeonhole yourself. It can be disconcerting to think you'd have to start at the bottom somewhere else when you've already put in a number of years into a job that's not getting you anywhere.

* Your mood ranges from angry to angrier. I personally have never experienced in the workplace, other than frustration at management. I can't say I get angry -- what's the point? It doesn't solve anything.

* You feel like hell. Life should make you happy for the most part. If the job situation is so bad it causes you emotional harm, it may be time to change the situation.

Because the trouble with waiting – to vest, to retire, to get promoted – is that it doesn't always pay off. There's nothing stopping employers from letting you go five minutes before you reach your goal. And the terms of your exit will be theirs, not yours.

The Career Planning Guide on About.com offers similar signs: Your job is making you sick; you find yourself being marginalized; you've outgrown your job; you receive a better offer elsewhere; and, work is interfering with family responsibilities. The same website offers resources for when you do decide to move on.

Question for those who have made the decision to move on from a decent job that was causing unhappiness: What made you decide to Just Do It™?

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