The heart is inherently dependent on Allaah in two ways: from the point of view of worship, which is the ultimate goal, and from the point of view of seeking His help and relying upon Him, which are the means to that end. The heart cannot be sound, or succeed, or find joy, or be happy, or feel pleasure, or be good, or be at peace, or find tranquility, except by worshiping its Lord, loving Him and returning to Him. Even if it attains all that it can enjoy of created things, it will not feel at peace or find tranquility, because it has an inherent need for its Lord, for He is the focus of its worship, love and seeking, and this is the only way to attain joy, happiness, pleasure, peace and tranquility.
…For if a person is helped to attain what he loves, seeks, desires and wants, but he does not worship Allaah, he will never achieve anything but sorrow, regret and suffering. He can never be free of the pain and hardship of this life except through loving Allaah sincerely, so that Allaah becomes his ultimate desire and he loves Him for what He is, and he loves anyone or anything else only for His sake, and he does not love anything for its own sake except Allaah. If he does not achieve this (level of love), he had not properly understood the true meaning “la ilaha ill-Allaah” or of Tawheed or of ‘ubudiyyah or of loving Allaah. There is something lacking in his eemaan and Tawheed, and he will suffer pain, regret and anguish accordingly.
[Excerpted from: Al-‘Ubudiyyah: Being a True Slave to Allah|By: Imam Ibn Taymiyyah (rahimahullaah)|Translated by Nasiruddin al-Khattab]