Vayehi bayom hashmini...
Shabbos is a time of cleansing, renewal and rejuvenation. A yid stops running around like a chicken without a head trying to bring in parnassa and has time to think, daven, learn and spend time with family. Shabbos should be a new beginning and the day after Shabbos should be 'Day One' of a new lease on life. The Gemara says that 'Vayehi' is an expression of pain. If the day after Shabbos feels like the eighth day of the week....
Likutei Imrei Chaim