We should worship that God who bestows reward for the smallest virtuous deed. God is the one who rewards humans even if they give even a sip of water to someone.
Once a woman was travelling through a forest. She saw a thirsty dog on the way. She weaved a rope from her hair and fetched some water from a well and quenched the thirst of the dog. The Holy Prophet (may peace and blessings of Allah be on him) said that God had accepted her act and will forgive all her sins although she had been sinful all her life.
(Malfuzat, Vol. 6, p. 26)