Gratitude is of two degrees, one of which is obligatory, which is doing obligatory actions and avoiding haraam things. This is essential and is sufficient as gratitude for these blessings.
Hence one of the salaf said: Gratitude means giving up sin.
And one of them said: Gratitude means not using any blessing to help one to disobey Him.
Abu Haazim al-Zaahid mentioned gratitude of all the physical faculties: (It means) refraining from sin, and using them to help one to do acts of obedience.
Then he said: As for the one who gives thanks with his tongue but does not give thanks with all of his physical faculties, his likeness is that of a man who has a cloak and takes hold of the edge of it, but does not put it on, so it is of no benefit to him against cold or heat or snow or rain.
The second degree of gratitude is that which is mustahabb, which is when, after doing obligatory actions and avoiding haraam things, a person does supererogatory acts of worship. This is the degree of those who have gone ahead and closer to Allaah.