"לא בשמים היא לאמור, מי יעלה לנו השמימה, ויקחה לנו וישמיענו אותה ונעשינה" [דברים ל:יב]
"It [this mitzvah / or torah] is not in the heavens, that you should say 'who will go up to the heavens and bring it to us, and teach it to us, that we may do it"
The Torah tells us that it is all within reach. The Torah is not an esoteric wisdom that is totally inaccessible. Rather, Hashem has brought it down to earth (double meaning intended) for us to be able to perform it. As a further passuk proclaims "… it is within [the abilities of] your mouth and your heart to accomplish it…".
Rashi, when explaining this passuk, tells us that if the Torah were in the heavens, we would be obligated to go up and get it. This hints at a tremendous reality. We have the ability to ascend to the highest spheres and live a life of Torah – even if it were in the heavens ! If the Torah was "up there" we should be able ( and be obligated ! ) to live a heavenly life, divorced from the lower parts of the flesh and blood world.
But Hashem doesn't want that. He brought the Torah down into the little, daily details. Hashem wants us to wash our hands in the morning, He wants us to smile when we say thank you. He wants us to thank Him whenever we have a tasty bite of chocolate and He wants us to notice the table settings and their sparkle.
Why ? Why would Hashem, who gave us the highest, loftiest, wisdom and the deepest, holiest concepts, want us to busy ourselves with the mundanities and trivialities of daily existence ? because it is no trick for something huge and powerful to perform a huge and powerful action. It is no great feat for an enormously strong man to carry out an act of great strength, it is simply in his nature. But, when a powerful man gently takes a fragile flower in his hand – that is an incredible act.
It is insufficient for us, who are powerful and gifted enough to be able to reach the very heavens with our actions, to simply dedicate our "big acts" to Hashem. We should also realize, and accordingly, perform, our "little acts" for Hashem too. After all, it isn't in the heavens – it is close to our hearts and within reach of our mouth.