For me it's personal pride, closely followed by money and a certain amount of autonomy. I am very motivated by earning a good salary.

I think disgust is a really good motivator, too. I work with a lot of people from a 3rd party support company who are so visibly de-motivated and poorly skilled that I spend much of my time privately wondering how on earth they can be happy with themselves when they're doing such a piss-poor job. They motivate me to do my best not to be like them. We all have our bad days, but when every day is like that it's time to look at your options.