I don't know about you, but no matter how much I try I can't just spontaneously summon up focus if my mind's not commmited to it. I was that way in school, in uni and now in work.

Working in an office pretending that I can focus on the task at hand whenever required by the roster of office life is one of the biggest charades I've ever performed. It's not possible for me and I piss around on the internet on their time when I am unable to focus. I don't feel that's an abnormal situation for people, either, as it seems many of my colleagues also do it.