What is the ruling on one who feels in their prayer as if they are merely performing an obligation and nothing more?

The lack of feeling the sweetness of worship stems from a loss of sensation for it. To attain the sweetness of worship, the worshiper must feel that every act of worship brings him closer to Allah, that Allah is watching him while he performs it, and that he may die after it, which motivates him to perfect it. The Prophet was asked about ihsan (excellence) and he said: "It is to worship Allah as if you see Him, for if you do not see Him, He surely sees you." Khushu' (devotion/humility) is the core and spirit of prayer, and prayer without khushu' is like a dead body. Moreover, it is one of the greatest causes of success, as Allah Almighty said: "Successful indeed are the believers those who are humble in their prayers." Khushu' is achieved by the servant's turning to his prayer and turning away from worldly matters, being keen to perform prayer in its prophetic manner, reflecting on the adhkar (remembrances), and contemplating the meanings of the verses. One must distance himself from what distracts the mind, and supplicating for khushu' is one of the greatest means of attaining it. The majority of scholars hold that the absence of khushu' diminishes the reward of the prayer but does not invalidate it.