The Dangers Of Humility
Sometimes excessive humility can cause a person to fall away from serving Hashem. One perceives oneself as so lowly, that one cannot believe that a human being can elicit an abundance of blessing to all worlds by virtue of one's prayer and Torah study, for indeed, even the angels are sustained by human prayers and Torah study. If one would believe this, one would serve Hashem fervently with joy and awe, and out of a sense of abundance. One would make sure that every word one utters and every movement one makes is done properly.
(Rebbe Yaakov Yosef of Polonoye)