David Hamelech proclaimed in Tehillim (Chap. 121), "Hashem is your shadow." Chazal explain that just as your shadow mimics your motions, so too Hashem "mimics" your actions. This concept applies not only with regard to daily Hasgacha pratis - it is the manner that Hashem executes judgment on Rosh Hashana. "Says Rava, if one overlooks others' transgressions [toward him]; Hashem will overlook all his sins, as the pasuk states, 'He pardons sin and overlooks transgression.' For whom does He pardon sin? For he who overlooks [another's] transgression" (Rosh Hashana 17a).
Rav Wolbe writes (Alei Shur vol. II pg. 430) that this is a phenomenal means of achieving a favorable judgment on Rosh Hashana. If Hashem meticulously counts one's many transgressions that were carried out over the course of an entire year, he might be in serious trouble. However, Chazal revealed to us that it all boils down to the way we treat others. If we are offended by another, and instead of being quick to retaliate, we overlook his misdemeanor - we have in effect saved our very selves from punishment. This obligates us to put special emphasis on our interpersonal relationships during this time of year.
However, it is not just the judgment aspect of Rosh Hashana that requires us to improve our middos. Accepting upon ourselves His Heavenly Kingship also necessitates a middos workshop as seen clearly in the following Chazal. "'And He was King in Yeshurun' When? 'When the leaders gathered together and the tribes of Yisrael were united.' Rav Shimon bar Yochai said this is analogous to a man who took two boats, tied them together, and built a palace upon them. As long as the boats stay tied together, the palace remains standing. Once they separate, the palace collapses. So too, as long as Bnei Yisrael remain united, Hashem has a foundation on which His Kingship can rest" (Sifre, V'zos Habracha). If Hashem is to be our King, then we must be His nation. This requires that we be united. Especially at this time of year we must go out of our way to befriend others, love our fellow Jew, and pursue peace at all costs.
Rav Wolbe adds that it is written in 'seforim' that when saying kedusha, there is a minhag to look to the right and left before saying kadosh, kadosh, kadosh. This is because we declare in the kedusha that "we will sanctify His Name in this world just as the angels sanctify Him in the heavens." The angels dwell in complete harmony and therefore sanctify Hashem with total unity. Hence, if we are to sanctify Hashem just as they do, we must be sure that we are at peace and in complete harmony with all those around us. Therefore, we turn to the right and the left to confirm that we live in complete harmony with those around us. If this is true about every time we say kedusha, how much more so does it apply on Rosh Hashana!
As Rosh Hashana approaches, we have these two significant reasons to make an extra effort to overcome our negative middos, and accentuate our positive middos. Though at other times of the year we might feel the need to work on each middah individually and at a slower pace, we do not have that luxury during Elul and Rosh Hashana. We must distance ourselves from anger, hatred, jealousy and bearing a grudge as far as possible. Moreover, before shachris we should accept upon ourselves to love our fellow Yidden and overlook their offenses. As Chazal tell us, this is the way to guarantee a positive judgment.
May we all merit a Kesiva V'Chasima Tova!