^Immune System Boosters: Everyday, get Exercise (Stress
reliever), Get Outside (Vitamin D + fights against depression)
and even, get this - Get Dirty. "Exposure to friendly soil
bacteria could improve mood by boosting the immune system just
as effectively as antidepressant drugs" and its not just for
kids - adults benefit from exercise, dirt, outdoors. Take Zinc.
So says Doctor Ken (not a licensed doctor, just a guy who reads
way too much)^