I think that many people enjoy learning. But they enjoy learning different things. Developer might enjoy learning new programming language. Artist might enjoy learning new painting techniques or may be new Photoshop features. But if you will ask artist to learn Lisp to write image processing algorithm, probably that won't be interesting for him. And if you will ask developer to learn Photoshop to add shadows to that icon, probably he won't be happy either, unless he happened to like both programming and painting at the same time.

So may be it's important to understand your target audience.

Of course some people just hate their job and the only thing that makes them happy is the end of the day...