I believe people get old physically and mentally. If as person has a good outlook on life and deal with things in a positive manner they remain mentally youthful. They choose not to be the victim which brings on stress and all types of psychological abnormalities.
A person ages physically if they do not take care of their bodies. they need to exercise and eat the right foods. Avoid substances that destroy the body such as drugs and alcohol.
These type people don't seem to age as quickly as others who do not take these steps to stay healthy.