The self-determination of those judged to be competent is generally respected. However, when a person is faced with a serious illness, the new emotions resulting from this state may change their values and goals. In addition, they may not be able to determine their priorities themselves and may require help from family members or healthcare providers to do so. The consideration of this leads to an examination of what is meant by respect for self-determination, the role of family members and healthcare providers in shared decision making, and possible practical instruments for decision-making.