There's a large degree of comfort in your current responsibilities and the company you're familiar with. Part of your brain knows you're capable of more, but another part is fraught with self-doubt and wakes you from sleep at 2am in a cold sweat, beaming an image of you in your new job frozen by ignorance, out of your depth, and facing termination.

So how do you know when it's time to go? Here are 4 indicators that it's time to make the change.

1: You know you aren't performing to the best of your ability
We all go through slumps, bad days, even bad weeks when we just don't care, don't give it our best... but what if that week turns into months? If you just don't have what it takes to give it your best, something needs to change. This is a common sign of burnout or of being overworked, under-worked, under-challenged or out of your depth.

If lack of motivation is the only issue, it may be possible to effect change within your current company by requesting different responsibilities, more training or another position. But if none of these options is available, it's time to update your resume.

2: You take inventory of your job's pros and cons... and the cons win
If you're having a hard time deciding whether to change jobs, try this simple exercise. Create a document with two lists — things you like about your current job, and things you dislike. Next, apply a weighting to the items. This can be as simple as a value from one to 10 to rate the importance of each factor.

 Next, add up each list. If the cons outweigh the pros, it's probably worth at least considering a change. If nothing else, this exercise will force you to focus on what you specifically do and do not like about your current position and give you a more concrete idea of what to look for in a new position.

3: You look for ways to improve your current situation but you can't turn it into what you really want
Another useful exercise is to take your list of pros from the previous exercise and expand upon it. Elaborate on the items already on the list and add other items you wish you could claim about your current position. When you're finished, review the list for items you may be able to make happen at your current company.

If you want more responsibility or more flexible hours, you might be able to work that out, whereas if you work for a missile manufacturer and happen to have developed pacifist beliefs since accepting the position