Excellent choice of an image!
There are reasons for us to push ourselves to achieve more during the day.
For me that reason is the image I have on the level of achieved results.
Internally, I'm usually aware that I can't achieve it all in a day, but I still do it believing that this is the best way to reach the set goal faster.
I absolutely believe in striving to achieve as much as possible and setting goals, but what I believe in more than that is the balance. We are never going to be able to do it all in this life. But if we do our best and are content with that, we will feel much more satisifed than if we create neverending goal cycles for ourselves.