The Baal Shem Tov taught:

You must know that everything depends on you. That with your every mitzvah, the universe resonates in blissful harmony that heals and nurtures. That with a single sin, the entire cosmic symphony falls apart in a cacophony.

Because if you pretend to be humble, saying, “Who am I, this lowly creature, that anything I do should have significance in the cosmic scheme of things? Who am I, that the Creator of this infinitely-sized operation should take notice of my deeds?”

—with those words, you will free yourself to do however you please, bringing your entire world down with you.

But when you are aware that the Master of the Universe kisses your lips with every word of Torah or prayer that you utter, then you will say each word just as it should be said, with love and with awe. And when you truly believe that with each mitzvah you are in embrace with the Infinite Light Himself, then your entire day will be filled with beautiful deeds that shine.

As for misplaced humility, the Talmud tells us, “The humility of Rabbi Zecharia ben Avkilus destroyed the Holy Temple and exiled us from our land.” -- Keter Shem Tov 145. See also Bati Legani 5720.