Gra (Even Shleima 2:12): All the pleasures that a man enjoys in this world will become bitter in the grave. The lusting flesh will be punished in the travails of the grave. There in the grave, judgment will be exacted from every limb of his body which enjoyed material pleasure in this world that was not part of a mitzva. In fact the pleasure he experiences in this world will turn into the fiery venom of a snake. And even though the tzadikim will suffer the travails of the grave, but not for partaking in gratuitous pleasure in this world - since their intent was always for the sake of heaven. In fact for the tzadikim all the pleasure they have is considered as a mitzva since it is done for the sake of heaven and their eating is considered as a sacrificial offering.