Reb Avraham Pollak zt'l, the mashgiach of Slabodka, asked the Chazon Ish zt'l, "Why do we go through the process of doing teshuvah in Elul and during the yamim noraim? When Cheshvon comes around, we will be back to our old selves again!"
The Chazon Ish answered that it is all worthwhile for a few days of closeness to Hashem. A moment of teshuvah is significant, even if it doesn't last.
At another time, the Chazon Ish explained that if it weren't for these days, we would easily fall "into the mud," of aveiros and bad habits. So, perhaps the teshuvah won't last, but at least this process prevents us from falling even farther away.
Someone asked the Slonimer Rebbe zt'l the same question. What is the purpose of Elul and teshuvah if it won't last? He said that chimney cleaners bathe each night, although they know they will become dirty again the next day. They still choose to cleanse themselves because they appreciate the feeling of being clean. Similarly, during Elul, we strive to purify ourselves. Even if the effects are temporary, the effort is worthwhile. A moment of spiritual cleansing is precious to Hashem and to us.
Sailors use rope to tie their ships to the pier. Since the rope is in the water and has wear and tear, the sailors must constantly change the rope. Someone once watched the sailors changing a torn rope for a new one, and he asked, "What is the purpose? Soon this new rope will be worn out, and you will have to change it again." The sailors replied, "What other solution do you have? If we don't tie down the ships, they will float away into the sea."
Reb Chaim Friedlander zt'l told this mashal to explain the importance of Elul. It is indeed likely that we will fall away from our resolutions for the new year, but we need Elul to anchor ourselves down. If we don't have Elul, we will undoubtedly fall away from Hashem.
We recommend that a person take on a kabbalah that is easy to keep. If it isn't too much, it can last for a long time. However, as we see now, even if chas v'shalom the teshuvah doesn't last, the process is precious and has many benefits.
