Causes of the flu. The flu is caused by influenza virus types A, B, and C. Both type A and type B flu viruses are responsible for the seasonal outbreaks of flu. Type A flu viruses are found in many different animals, including ducks, chickens, pigs, and horses. Influenza B viruses circulate widely only among humans.
Find healthy ways to manage stress. Consider healthy, stress-reducing activities such as meditation, exercising or talking things out with friends or family. Keep in mind that unhealthy behaviors develop over time and can be difficult to change. Don't take on too much at once.
1 Try to get at least 30 minutes of activity each day, at least five days a week. Exercise relieves stress and helps you control your weight.  Don't let stress build up. The chemicals your body makes in response to stress make your heart beat harder and faster and your blood vessels tighten.