The construction of the Mishkan
(the Holy Tabernacle) has a lesson to teach us in our daily lives. When the Jewish people were traveling in the desert, some of their stopovers lasted only one day or night. Nonetheless, at every stop they reassembled the Mishkan
with all its details just as they did at a place where they spent eighteen years.
This is a lesson for each and every Jew in how to conduct himself in his service to G-d and the pursuit of his mission in this world. One should not consult the calendar or the clock to estimate if what he is about to do will last for eighteen years. Nor should he think that if whatever he is doing is unlikely to endure for more than a single day or night then perhaps it is not worth the effort. For just as G-d is eternal and unlimited and undefined by time, so, too, all the actions of a Jew that are connected with his service to G-d are eternal - even if in a few minutes he will find himself involved in another pursuit.
Igros Kodesh of the Rebbe, vol. 10, p. 107