Shortly before Moshe passed away, he asked Hashem to appoint a leader over Bnei Yisrael who would stand in his stead. The Torah records Moshe's request and the unique manner in which he addressed Hashem. "May Hashem, the G-d of the spirits of all flesh, appoint a man over the nation" (Bamidbar 27, 16). Rashi explains Moshe's choice of words as follows: He said to Hashem, "It is revealed and known to You the thoughts of each person and how their thoughts differ from one another; appoint a leader who can tolerate each and every one of them with their individual attitudes."
Rav Wolbe (Shiurei Chumash) explains that a leader is someone who is broadminded. He isn't one who decides on a specific approach to serving Hashem and then forces it upon all his constituents. Rather, a leader is one who uses his talents and strengths to aid each person in their individual path of avodas Hashem.
Rav Chaim Soleveitchik zt"l was the embodiment of this type of spiritual leader. He had many disciples (Rav Isser Zalman Meltzer, Rav Shimon Shkop, Rav Baruch Ber Lebowitz, and the Brisker Rav, to name a few) who they themselves became great leaders; but each one had their own inimitable way of doing things. He polished their individual qualities, and turned each one into a brilliant - and unique - diamond.
Mastering the trait of tolerance is a prerequisite for becoming a truly great leader. However, this is not a quality that is imperative solely for a leader. Each and every one of us must make an effort to acquire the trait of tolerance, lest we look down on another's manner of avodas Hashem. Instead of thinking, "Why does he have to dress, behave, or daven that way?" we should think, "Isn't it amazing that everyone acts differently, but they are all striving to serve Hakodosh Baruch Hu?"
There is no better time than the Three Weeks to work on acquiring this trait. It does wonders for one's bein adom l'chaveiro, and will definitely hasten the end of the galus which was brought about through sinas chinom.