A good article from HBR which explains why I have "busy productive" and "busy unproductive" times…
Of course there really isn’t a whole lot of "down-time" at Microsoft, but you don’t always get the feeling you’re getting things done (low focus)… And then there are folks that go about doing their work, and yet you don’t get the feeling that they’re living up to their potential (low energy).
Enjoy.
http://hbr.harvardbusiness.org/2002/02/beware-the-busy-manager/ib