I was once privileged to hear from my father-in-law [Rabbi Yosef Yitzchak Schneersohn, the sixth Lubavitcher Rebbe] that his father, Rabbi Sholom Dovber, of saintly memory, was once asked, "What is a Chabad-Lubavitch Chassid?"
He replied, "A Chassid is like a street-lamp lighter." In olden days, there was a person in every town who would light the street-lamps with a light he carried at the end of a long pole. On the street-corners, the lamps were there in readiness, waiting to be lit; sometimes, however, the lamps are not as easily accessible. There are lamps in forsaken places, in deserts, or at sea. There must be someone to light even those lamps, so that they may fulfill their purpose and light up the paths of others.
It is written, "The soul of man is the candle of G‑d." It is also written, "A Mitzvah is a candle, and the Torah is light." A Chassid is one who puts his personal affairs aside and sets out to light up the souls of Jews with the light of Torah and Mitzvot. Jewish souls are ready and waiting to be kindled. Sometimes they are close, nearby; sometimes they are in a desert, or at sea. There must be someone who will forgo his or her own comforts and conveniences, and reach out to light those lamps. This is the function of a true Chabad-Lubavitch Chassid.
The message is obvious. I will only add that this function is not really limited to Chassidim, but is the function of every Jew. Divine Providence brings Jews to the most unexpected, remote places, in order that they carry out this purpose of lighting up the world.
May G‑d grant that each and every one of us be a dedicated 'street-lamp lighter,' and fulfill his/her duty with joy and gladness of heart.