What is the reason for not feeling longing for Allah, Paradise, and the Messenger (peace be upon him), and the inability to devote oneself sincerely to Allah and rectify the heart, despite reading the biography of the Messenger, the Beautiful Names of Allah, and descriptions of Paradise?

Reading alone is not enough to achieve great spiritual deeds. Rather, it requires sincerity with Allah, striving against one's self, and contemplating His names, attributes, and words. One must also associate with righteous people, read the biographies of the pious predecessors and emulate them, understand the ailments of the heart and their cure, and be diligent in seeking beneficial knowledge, remembrance [dhikr], supplication [du'a], and constant self-reckoning.