I remind myself that all work isn't created equally. Just because I'm busy doesn't mean that I'm being productive.
I imagine that every kind of work has its fake-work and make-work. For example, as a writer, I remind myself:
create, don't fiddle around with italics and formatting
typing isn't the same as writing
cruising around the internet isn't the same as "research"
answering emails, checking Twitter and Facebook, and similar tasks, while important, must not be allowed to get in the way of writing and thinking
if I'm finding it very hard to write, I should stop trying to write and instead, start thinking harder
if I'm finding it very easy to write, I'm probably falling into cliché and should start thinking harder
Of course, one of my Secrets of Adulthood is that the opposite of a great truth is also true, and I have several resolutions aimed at helping me not to worry constantly about being efficient, but instead, to force myself to wander and schedule time for play. Sometimes, I work best by doing things that don't look like "work."
In your job, do you have to fight the urge to do fake-work and make-work? What form does yours take?