When you desire something, your joy depends on that something. If it is
taken away, you are miserable; if it is given to you, you are happy. But
only for the moment! That too has to be understood. Whenever your
desire is fulfilled it is only for the moment that you feel joy. It is
fleeting, because once you have got it, again the mind starts desiring
for more, for something else.
Mind exists in desiring; hence mind can never leave you without
desire. If you are without desire, mind dies immediately. That's the
whole secret of meditation.