The Torah reading Tetzaveh, that we read this week

The Torah reading Tetzaveh, that we read this week, continues from the previous portion to enumerate the commandants that pertain to the various details of the Sanctuary. These portions contain the "instructions" on how to make the Sanctuary's vessels, as well as the holy garments that were worn by the kohanim (priests).
The very last mitzva (commandment) we are told of relates to the building of the golden altar and the incense offering that was made upon it. "And you shall make an altar to burn incense upon...every morning when he dresses the lamps...a perpetual incense before the L-rd, throughout your generations." Because the incense offering concludes the list of these mitzvot, we may infer that it was the culmination of all the different services that were performed in the Sanctuary.
Every day the incense offering was made by a different kohen. Only the kohen was allowed to enter; no other person was permitted to be present when the mitzva was performed. The kohen was alone in the Divine Presence of the Holy One.
The same holds true for the G-dly service of every individual Jew. The highest level we strive for is to serve G-d without fanfare or publicity, especially when standing alone in G-d's presence. In a certain sense, every Jew is considered to be a "kohen," as G-d commanded, "You shall be to me a nation of kohanim." Just as the kohanim were chosen to perform the service in the Sanctuary and Holy Temple, so too has every Jew been chosen to serve G-d, not only for his own sake but for his people as a whole.
The best way to perform any mitzva, particularly the mitzva of tzedaka (charity), is not under the glare of spotlights or in front of a camera. A Jew doesn't observe a mitzva in order for his good deed to be written up in the newspapers. The most perfect manner of doing a mitzva is in secret, so that only G-d and the participant are aware of it - just like the incense that was offered by the kohen in the presence only of G-d.
Furthermore, just like the incense offering in the Sanctuary, when a Jew observes the Torah's commandments in private, it likewise causes the Divine Presence to dwell in the physical world.

Adapted from Likutei Sichot of the Lubavitcher Rebbe, Volume 1