I think that's the problem for many (if not most) people who are satisfied with their job--a lack of autonomy and ownership.

For example, take fry cook A, who works at Wendy's, and fry cook B, who works at an independent restaurant where the owner gives him a good deal of creative control.

Fry cook B's job is to make the best damn hamburger he can, and he get's to use his brain a bit. Fry cook A's job is to make the exact same hamburger as every other cook at every other Wendy's in the country.

Most humans just aren't very happy trying their best to act like a robot.