We do not know the day, nor the hour of our death. It is a simple fact, which should encourage us to live each day as if it could be our last.
With this in mind, we can pray to God and ask him for the grace to die with a good and peaceful conscience. This means that we are at peace with God and do not have any regrets, wishing that we had lived a better life.
Here is a prayer from the Raccolta that asks for this special grace.
O God, who hast doomed all men to die, and hast concealed from all the hour of their death, grant that I may pass my days in the practice of holiness and justice, and that I may be made worthy to quit this world in the peace of a good conscience, and in the embrace of Thy love, through Christ our Lord. Amen.