When you have a particularly tight timetable, you may find it helpful to write down specific things you do not plan to do. Write down the time wasters and time robbers you will avoid. For example, you may write down that you will not answer phone calls unless they are truly urgent, you will not accept visitors, or you will not file anything today. Not-to-do lists can be almost as important as To-Do lists.

Edward Charlesworth and Ronald Nathan, 1982, Stress Management