When a person's physical, emotional, intellectual, social development or spiritual functioning is compromised, this deviation from a healthy normal state is called illness. Illness creates stress that in turn harms individuals. Irritation, anger, denial, hopelessness, and fear are behavioral and emotional changes an individual experiences in the phases of illness. A variety of factors influence a person's health and well-being.

For instance, risk factors are connected to illness, disability, disease, or death. In general, the following groups represent risk factors:

• Behavioral risk factors relate primarily to "actions" the individual takes. It can be modified or eliminated by changing one's lifestyle or behavior. Examples of behavioral risk factors include a lack of physical activity, poor nutrition, tobacco use, and excessive alcohol consumption.
• Physiological risk factors are associated with a person's body or biology. These may be influenced by genetics, lifestyle, and other factors. Examples include being overweight and having high blood cholesterol or high blood pressure.
• Demographic risk factors relate to the overall population, such as age, gender, and population subgroups.
• Environmental risk factors are external, and include physical, chemical, biological, or occupational factors impacting someone's health. Examples include exposure to pollutants like heavy metals and asbestos fibers.
• Genetic risk factors are determined by a person's genes. Some illnesses, like cystic fibrosis and muscular dystrophy, are solely caused by a person's "genetic makeup." Other diseases, including asthma or diabetes, result from the interaction of a person's genes and environmental factors.