Al-Hasan al-Basree (Rahimahullaah) said, "The believer is like a prisoner in this lowly world, who tries to free himself from its shackles and chains, never feeling secure in it, until the day he meets his Lord." [az-Zuhd by Ibn al-Mubaarak]
If you don’t find sweetness and joy in the deed you perform, then doubt its sincerity, for Allah is Ash-Shakur(Most Appreciative and Rewarding).