The Previous Rebbe related:
“On the Shabbos when the month of Elul was blessed in Lubavitch, although it could still be a clear, sun-filled summer day, the atmosphere had already changed. One could already begin to sense the scent of Elul; the wind of teshuvah had already begun to blow.”
The explanation is as follows:
Although the avodah of Elul is “Ani LeDodi” — “I am my Beloved’s”, an awakening from below, and only afterward comes “VeDodi Li” — “and my Beloved is mine,” an awakening from Above, nevertheless, even the awakening from below comes through a giving of strength from Above.
This is also why this sichah concerning the month of Elul was delivered during the month of Nissan, whose theme is a drawing down from Above.
This is also the meaning of the expression “a clear, sun-filled day.” It alludes to the revelation of “Hashem is a sun”—a revelation from Above, an isarusa dele’eila.
Through this Divine assistance from Above, one comes to the avodah of teshuvah.
Teshuvah is associated with both “scent” and “wind.” The idea of teshuvah is that a person should reach the level of ruach, spirit, so that “the spirit shall return to G‑d Who gave it.”
Through this one also merits the level of “scent,” the revelation of Mashiach, concerning whom it is said: “He shall be imbued with the scent of the fear of Hashem.”
The avodah of teshuvah during the month of Elul is also comparable to air.
Just as a person constantly requires air, and obtaining it does not require special exertion, so too with teshuvah: during Elul, teshuvah is readily accessible, like the very air one breathes.



