Ibn Qayyim al-Jawzeeyah 751 AH (may Allah have mercy on him) said:

اذا لم تجد للعمل حلاوة في قلبك و انشراحا فاتهمه, فان الرب تعالى شكور

“If you do not find sweetness in your deed and comfort in your heart, then blame the deed. For indeed, the Lord, the Most High, is ash-Shakoor.

He continued to explain:

“Meaning, that it is a must for a person to be rewarded in the worldly life by tasting the sweetness of his deed, finding the sweetness of it in his heart, strengthening his comfort, and coolness in his eyes. If these things were not attained then (shirk) has entered into it.”

[Madaarij Saalikeen: Manzilatul Muraaqabah]