During the weekday, we feel lack—because we’re more distant from Hashem. But on Shabbos, we can feel much more easily that we have everything. And just as on Shabbos we feel satisfaction and fullness more easily, so too during the weekday we feel the lack more keenly. But this doesn’t mean that we must celebrate and marinate in the lack. We must serve Hashem with this feeling, with the great avodah that’s called for when we feel lack.
The avodah is to first turn to Hashem. To recognize that we can’t do anything on our own, and only Hashem can give us what we need. But then, the person must tell himself that somewhere within him, the shefa has already been delivered... This Yid takes his feelings of lack and showers them with thoughts of emunah and gratitude—and then his “prayer” becomes “praise.” From “weekday,” he is transformed into “Shabbos.” He began with Tishah b’Av and he concludes with Simchas Torah.
This ability to experience fullness and satisfaction during the weekdays directly draws from the holiness of Shabbos. Because this is the aura of Shabbos, and on Shabbos we can access this feeling. Once we internalize it, we can merit for קדשך משבת קדושה המקבלים ימים ששת, for the six days of the week to derive kedushah from Your holy Shabbos.