Through the ministry of the priest, Jesus touches the sick to heal them from sin – and sometimes even from physical ailment.
“When the Sacrament of Anointing of the Sick is given, the hoped-for effect is that, if it be God's will, the person be physically healed of illness. But even if there is no physical healing, the primary effect of the Sacrament is a spiritual healing by which the sick person receives the Holy Spirit's gift of peace and courage to deal with the difficulties that accompany serious illness or the frailty of old age.”
There is no need to wait until a person is at the point of death to receive the sacrament. A careful judgment about the serious nature of the illness is sufficient. It is not for those who are dealing with most mental conditions, stress, headaches, arthritis, allergies, physical injuries, flu/fever, or even for some cancer patients, provided that the individual at the moment has not started to be in danger of death. It is the sacrament which prepares the soul for the proximity of death.