"The Torah is acquired by means of forty eight qualities...[among them the quality of] loving reproof" (Avos 6:6). We find another statement of Chazal which highlights the greatness of one who acquires this quality: "Rebbi says, 'Which is the proper path that a man should choose for himself? He should love reproof, for whenever there is reproof in the world, pleasantness comes into the world, goodness and blessing enter the world and evil departs from the world'" (Tamid 28a). What is so unique about the quality of loving reproof that it brings so much bounty in its wake?
Rav Wolbe (Daas Shlomo) explains as follows. Yeshaya Hanavi (5:20) cried out, "Woe to those who speak of evil as good and good as evil, who make darkness into light and light into darkness, who make bitter into sweet and sweet into bitter." These weren't merely poetic musings. If Yeshaya said it, he really meant it. While in the physical world such extreme errors are very rare and generally caused by severe illness, in the spiritual arena they are all too common. Yet, truth be told, these spiritual mistakes are also the result of ailments.
Rabbeinu Yonah (Shaarei Teshuva 4:1) writes that just as there are illnesses of the body, so too there are illnesses of the soul i.e. transgressions and negative middos. (The same idea is mentioned by the Rambam in Shemoneh Perakim and the Ramban in Beha'aloshcha 10:4). Just as a physical illness demands the therapy of a physician, likewise, spiritual illnesses requires therapy. Chazal tell us that this world can be compared to nighttime where a person's vision is clouded by the darkness and therefore he mistakes poles for people. A person falters and transgresses when his spiritual vision became clouded by the "darkness" pervading this world. In summation, spiritual ailments all stem from a lack of clarity.
Rashi (Bereishis 20:16) explains that the literal translation of "tochacha" (reproof) is a "clarification of ideas." The mitzvah to give tochacha to a fellow Jew, does not mean to shout "crook," rather, it entails clarifying for the offender the cause and basis for his mistake. Since a lack of clarity causes transgressions, gaining clarity is the remedy for spiritual ailments.
Rebbi (above) did not ask, "Which is the proper path to which a man should cling?" as mentioned in the Mishna in the second Perek of Avos. Rather, he asked, "Which is the proper path that a man should choose? The word she'yavor ("should choose") is synonymous with the word she'yivror which means "to clarify". Rebbi was asking which path leads a person to clarity. To this he answered, that one cannot rely on his subjective perception of himself to achieve clarity. Rather, if he loves hearing tochacha (reproof) from others, this quality will lead him to achieve complete clarity. By achieving clarity one escapes the spiritual "darkness" that abounds in this world, thereby allowing him a clear vision of what is good and what is evil. Hence, loving reproof causes "evil to depart from the world" and "blessing and goodness" to fill its place.
Clarity might be the spiritual panacea, but for many it is a hard pill to swallow. It is too difficult for them to hear that they are making a mistake. Many people sacrifice years of their lives to mistakes made due to a lack of clarity of vision; they could have asked for advice but they didn't. A little pride is simply not worth the price. Ask a mentor or even a friend for an objective opinion on a life decision. The clarity gained by such an encounter is immeasurable!