Mostly , though , I was trying to distract you from thinking about work . " " Valiant effort , but quite a task to take on . The last time I did n't think about work at all was ... " He paused , bringing a finer to his chin to tap it in mock thought . " Three weeks ago . "

Why was he tapping his chin in mock thought at the statement ?
It was a humorous way of replying that it is nearly impossible for him to forgo contemplating about his job .