Uhm, that reminds of the movie office space. Peter to Bob: "That's my only real motivation is not to be hassled, that, and the fear of losing my job. But you know, Bob, that will only make someone work just hard enough not to get fired. "

As I see it there are greater incentives than losing ones job, some sort of prize if one does really well. But a confirmation of a good done job is also sufficient sometimes.