In the old days there were physical constraints on the world of work. The speed at which the postman could bring memos to you, the size of your in tray, the fact that the cleaners expected you to be out of the office by a certain time and the need to be in your boss's physical presence to be confident he knew you were working.
These days all of those constraints have gone and people have to decide for much more for themselves when they are working and when they are not. They also have to decide "how" they are working too as the number of ways in which we can process information means that the nature of our attention can change from one moment to the next and the quality of our connection to the tasks at hand can vary with it.
As Joshua-Michele Ross writes in a recent blog post:
The ability to pay attention, focus and strategically disconnect will be a winning discipline of the next generation of business leaders.