I've worked the same job in the same office for 8 and a half years. Way back when I was being interviewed for the job, it was made very clear to me that this position was not a stepping stone to bigger things; this was it. There would be nowhere to advance. Some people might have been immediately turned off, but it was music to my ears.
I've never had the desire to climb the corporate ladder and work my way up to the supposedly-coveted corner office. My goal was to find a job I like and give it my all. I didn't want to worry about looking for the next big thing or fighting for a promotion or seeing if I could eventually utilize my experience elsewhere for a fatter paycheck. I just wanted to get a job, be awesome at it, and stick with it. I'm sure it sounds like I'm not ambitious and that I've become complacent, but that is not the case.
Doing the same job for several years may sound like monotonous drudgery. I suppose that can be true, but it doesn't have to be that way. Although I obviously deal with much of the same each day, there are ways to keep things enjoyable and to improve myself and my work and expand what I do.