The Torah tells us that the first mitzvah performed each and every day in the Beit Hamikdash was that of Terumath Hadeshen--the cleaning of the ashes that had accumulated due to the constantly burning fires of the altars. "Janitorial work" thus was the fulfillment of the Divine will. Setting up chairs, taking out the garbage, and sweeping the floors in order to beautify our own Mikdashei Me'at (miniature sanctuary, our shuls) is transformed into a mitzvah.
The lesson that the Torah wants to stress is that the essence of Judaism is helping others with the little things in life.
