Research shows that some personality characteristics are related to health. For example, people who are optimistic, self-disciplined and adaptable tend to maintain good health. A more active lifestyle, such as regular exercise, reasonable diet and good sleep habits, will reduce the risk of illness. Negative personality traits, such as anxiety, depression, irritability and pessimism, are related to health problems. Such people are more prone to mental health problems, such as stress, anxiety and depression, which will have a negative impact on their health. For example, long-term stress and anxiety can weaken the immune system and increase the risk of illness.