Research has established that severe psychological stress could have a negative influence on the body’s immune system. Now more research is done on the immune system as to how it could be boosted sufficiently in all people to fight against infections and cancer. A person who eats in a healthy manner and maintains an active life style would always have a good résistance against any infections. Healthy habits would result in strengthening of the immune system of the body. Several immunizations could be done against diseases as a result of new findings in the immunology research. Alcohol will have a negative influence on the immune system.