I tend to work in focus bursts of 30 to 45 minutes (sorry, yes that is why I put my cell phone in a different room when you tried to call) after which my mental energy drops and my brain is looking for distraction.

I recently found the antidode to pointless facebook and Twitter browsing: put an accoustic guitar in your office, play for a few minutes, and dive back into your work. I do not miss reading about those 5 mistakes every designer makes...