Why do we always think we can fit much more into a week off than we can?

I am usually pretty good at getting my to do list mostly completed.. this time round I have barely touched it and it's Friday already tomorrow :(  I didn't paint the front door, (red!) I haven't tackled the huge pile of ironing, I haven't finished clearing/tidying the top section of the garden...I haven't read much, I haven't listened to audio books, and I certainly haven't renewed my passport :( and I feel tired after losing most of yesterday due to son's brokendown jeep.. Either I need to buck my ideas up or set myself a more realistic to do list in future.. I haven't even been anywhere fun! 

SO do you think they will let me have an extra week off to recover from my week off where too much has got in the way of things I should have done?