We worry in the winter about getting sick, but in spring and summer clients are out and about more and may be bringing in all sorts of germs. Living a generally healthy lifestyle helps your body fight infection if it tries to attack.

“I tell my patients the way they eat, their physical activities and their overall behaviors play a large part in improving overall health,” says Dr. Julie Taylor, a family medicine physician at Advocate Trinity Hospital in Chicago. We already know what to do, but Taylor puts it into the context of boosting your immune system:

• Maintain a vitamin-rich diet. “It is not a coincidence that infectious diseases are common in poorer countries, where malnutrition and limited health care lead to weakened immune systems,” Taylor says. “The ability to fight off infection directly connects to nutrition, which means the body requires a regular supply of nutritious food.” Encouraging people to eat more vegetables and whole grains, Taylor specifies vitamins A, B2, B6, D and E as the most critical for proper immune function, while the evidence is less compelling about vitamin C.

• Don’t smoke! “Smoking causes inflammation in your lungs that your immune system has to constantly fight,” Taylor notes. “Cigarettes also contain high levels of tar and other chemicals that dampen the immune system. Together, these factors leave smokers much more susceptible to infection.”

• Limit alcohol. According to Taylor, binge drinking compromises the immune system for up to 24 hours after getting drunk, while the long-term effects of too much alcohol make heavy drinkers much more susceptible to diseases like pneumonia, tuberculosis and HIV.

• Manage stress. Excess stress lowers the body’s total numbers of T-cells, the white blood cells that are a critical part of the immune system.

• Exercise. Just as regular exercise benefits the rest of your body, it does the immune system good, too. Exercise improves heart health and helps immune cells to circulate.

• Wash your hands. Poor hand hygiene is the number one way that food-borne illness is spread, according to the Centers for Disease Control and Prevention (CDC). Wash your hands often with soap and water—certainly between clients!

“You may not be able to do anything about family history,” Taylor says, “but you can do a lot of other things to make sure you stay in good health and have a healthy immune system.”