From Celia’s Images in a Reflecting Pool: Journal Entries Inspired by A Course in Miracles; copyright 1995:
The re-entry problems at work on Monday are not physiological or even psychological for the frequently cited reasons. After “flight” on the preceding two days, the body gets up once again to “fight.” And the more relaxing the flight has been, the more likely the fight will bring fears.
One has let down one’s guard, and the ego doesn’t take kindly to peace. It knows its days are numbered if its owner should ever learn to choose Peace consistently.
MIRACLES EACH DAY 
More grace.