There are several factors involved in determining the type of preventive care a person needs. Of these, life expectancy may be the most important, as some types of preventive care (ie, flu vaccine) are helpful at all ages, whereas others (ie, screening for many types of cancer) have been found to be helpful only if life expectancy is more than 5 years when the screening is done. Determining which preventive care to undergo depends on weighing the likelihood that the person will benefit from the preventive measure (reduce disease or symptoms) against the likelihood that the person will experience harm (for example, treating a condition that otherwise would never have affected the person). Risk of mortality is based on functional status (an individual's ability to perform normal daily activities required to meet basic needs, fulfill usual roles, and maintain health and well-being) and number and severity of medical conditions. The most common causes of death for each age group are also important in determining which types of preventive care to recommend for a person. No matter what your age, the most important things you can do to prevent disease and be healthy are exercise, eat a healthy diet, and don't smoke.