Shukr: Gratitude
Al-Ghazali gave gratitude a whole book inside his Revival. After a hard stretch ends, the mind wants to hurry on to the next worry, and gratitude holds it still long enough to look back. The looking is the work: seeing what came, and seeing that it came from somewhere other than your own effort.
Luṭf: God's quiet kindness
Sufis use this word for help that arrives without announcing itself. Much of what holds a life together was arranged before anyone thought to ask for it: the door that happened to be open, the friend who happened to call that week. Anyone taking stock of good years finds that most of the care was never seen while it was happening.
If you tried to count God's blessings you could never number them: the gifts outrun the count
A line from the Quran that Sufis come back to constantly. Anyone who starts an honest list hits a snag, since each item opens into several more behind it, breath behind speech, people behind people. The list stays open because every good thing on it rests on others that never made the page.
I cannot count Your praise; You are as You have praised Yourself: thanks can never match its source
Words the Prophet used when his own ran out. Trying to thank someone in proportion to what you received puts a person in a bind, because the effort is honest and still falls short. Admitting the shortfall out loud takes the strain off, and the thanks keeps being spoken without pretending to be enough.
Tawfīq: the help from God that makes a good act possible
Al-Ghazali pointed out that the ability to thank is itself a favor, which calls for more thanks. The account never closes, and the person keeps finding that even the words being used to repay were handed over first. Gratitude then feels less like settling a bill and more like staying in touch with someone generous.