What is the reason for intense crying when remembering Allah, supplicating, or contemplating the affairs of Allah? Is it a feeling of shortcoming or fear of Allah?

Crying upon the mention of Allah Almighty is praiseworthy in Islamic law and indicates fear of Allah, longing for Him, and love for Him. Many hadiths have been narrated that show the virtue of this, among them that "a man who remembered Allah in solitude, and his eyes overflowed with tears" is one of the seven whom Allah will shade in His shade. And that whoever cries out of fear of Allah will not be touched by the Fire, as in the hadith: "A man who cried out of fear of Allah will not enter the Fire until milk returns to the udder," and "Two eyes will not be touched by the Fire: an eye that cried out of fear of Allah and an eye that spent the night guarding in the way of Allah." The overflowing of the eye is according to the state of the one remembering Allah: in descriptions of majesty, it is out of fear of Allah, and in descriptions of beauty, it is out of longing for Him.