I SO hear you!
My leave starts next Wed. (EDD: 11/27) and I can't wait, because my heart and head is just not "here" right now!
I could work longer, as I feel physically great--but I am just too distracted with everything to work in the focused manner that I usually do.
In fact, I was on this board 3 times today at work (and am still at work now!!!), when I should/could have been accomplishing other work related things! It's not that I won't get my "to do" task...