“…It is customary to sound the Shofar after Shacharis throughout the month of Elul, beginning on Rosh Chodesh…” –  Rema, Orach Chaim 581:1

מראש חודש ואילך מתחילין לתקוע אחר התפילה שחרית – רמ”א או”ח תקפ”א, א

The Rambam writes that the sounding of the Shofar conveys this message:

“Sleepers, be roused, from your sleep! Slumberers, wake from your slumber! Search your deeds and return in teshuvah…” (Hilchos Teshuva 3:4)

A careful reading of the Rambam’s words shows that the path to teshuva, repentance, is specifically a two-step process. The first step is to arouse and wake from your sleep or slumber, and the second, to search your deeds.

A person while sleeping has no conscious desire to disturb his sweet sleep and awaken. The same is true when a person is asleep spiritually; his spiritual state is entirely not of concern to him. On the contrary, he is complacent with his life and uninterested in disturbing his peaceful obliviousness. Therefore, his first step toward teshuvah must be to wake from his slumber and make himself aware of his spiritual condition. Only then, will he begin to earnestly seek teshuva.

This arousal alone, however, is not enough. To truly “return in teshuva” says the Rambam, you must “search your deeds.” In order for your resolve of teshuva to be genuine, meaning, to be truly determined to never again transgress G-d’s will, you must examine your conduct in detail and take notice of the specific areas in which you have failed in the past. For in order to withstand the temptations with which you struggled in the past, your vigilance in those particular areas must be especially strong and resolute.

When you “wake from your slumber” and then “search your deeds,” then you can successfully proceed to “return in teshuvah.”

—Likutei Sichos, vol. 9, p. 130