Barry Schwartz explores what motivates us to work in The New York Times: 

Of course, we care about our wages, and we wouldn’t work without them. But we care about more than money. We want work that is challenging and engaging, that enables us to exercise some discretion and control over what we do, and that provides us opportunities to learn and grow. We want to work with colleagues we respect and with supervisors who respect us. Most of all, we want work that is meaningful — that makes a difference to other people and thus ennobles us in at least some small way.

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Work that is adequately compensated is an important social good. But so is work that is worth doing. Half of our waking lives is a terrible thing to waste.

A complement to this essay is Daniel Pink's book Drive: The Surprising Truth About What Motivates Us.