R’ Noach Weinberg was really an introvert, but he saw a need in Klal Yisroel and therefore changed his nature. He also started 8 yeshivos before Aish HaTorah. When he went to get a brocho from his Rav, I think it was Rav Hutner, the Rav gave him three pieces of advice. He followed the first two, but only suceeded when he listened to the third which wasn’t to take on partners.
Regarding Rabbi Weinberg I heard that he was such an introvert that after speaking publicly he used to get sick he would be knocked out for hours! Truly extraordinary mesiras nefesh!