well that's a good answer, but not terribly practical. when it's coming up on month #6 of you emailing resumes, going to interviews and waiting for that one that pans out into an offer... with your savings getting to the end of the barrel and you wondering if you'll have to take cash off your credit card soon for rent -- you will take just about any job that's offered to you & not be too picky.
Even if you go from a less desperate position (searching for a better job while already employed), it can be tough. Took me 2 years to leave a place I hated; less time to go to interviews and job search when you're already working full-time. Plus the fear of getting caught by your boss. Plus the fear of leaving a place where you have built up some seniority to go somewhere new -- where you can be let go for no reason at all during the probationary period because they just "feel like you're not working out" (or they had a budget reassessment and realized they have to cut staff, or whatever).
You don't always get to choose where you work. And the downsizing/bottom-line driven society we live in means most of us live in ridiculous, unhealthy, obsessive fear of losing our jobs. But that's another conversation for another thread.