Koznitzer Maggid on the hint to our avodah in Elul in the parsha of ma'aser

Our parsha contains the halacha of bringing ma'aser sheni to Yerushalayim, and what to do when you can't transport it there:

Aser te'aser es kol tevu'as zarecha... Ki yirchak mimcha hamakom... v'tzarta bakesef v'nasata hakesef b'yadcha v'halachta el hamakom asher yivchar Hashem Elokecha bo (Devarim 14:22-26).

The Koznitzer Magid in Avodas Yisrael (see the Maor v'Shemesh as well) explains these pesukim as hinting to our avodah during chodesh Elul.

Eser = 10, gematriya the letter yud, is a hint to yirah (we see from the halacha of ma'aser that 10 has special spiritual significance).

Aser te'aser es kol tevu'as zarecha -- A person should always strive to imbue all that he produces with yirah. 

Ha'yotzei ha'sadeh shanah shana -- Not only this year, but even reaching back to previous years, to correct the past and elevate it.

Ki yirchak mimcha haMakom -- But even though we all know we have to do teshuvah, we all want to do teshuvah, sometimes a person feels so distant from Hashem that he feels like he can't make it.

V'tzarta bakesef, v'nasata hakesef b'yadcha -- Even if you feel you are going to fall short, don't give up. Hold that desire for teshuvah (kesef = desire, kisufim, as in the pasuk "nichsof nichsafti" [Braishis 31]) in your hands and don't let it go.

V'halachta el haMakom -- You are on the road, headed in the right direction back to Hashem.

Asher yivchar Hashem Elokecha bo -- And at some point you will reach that level which Hashem desires of you.