Desire, on this account, isn't really about the future: it's a memory of some past pleasure, projected forward and mistaken for a promise. Fear does the same trick with pain. Both keep the mind busy comparing right now to some other moment, which is why satisfaction never quite lands even when you get exactly what you wanted: you're still measuring it against the memory instead of feeling it directly. Today, when you notice yourself wanting something, ask what earlier pleasure it's echoing, and notice whether the wanting loosens once you've actually spotted the echo underneath it.
Desire is the memory of pleasure and fear is the memory of pain. Both make the mind restless. Moments of pleasure are merely gaps in the stream of pain.
Nisargadatta Maharaj, I Am That, Ch. 3 "The Living Present" (trans. Maurice Frydman, ed. Sudhakar S. Dixit)