Be in Life

Recently, I have seen a lot of my friends got sick because of the flu season. Today, my boss told me that he got a cold also. We have 5 people in a small office, 3 of them got sick. I wonder if mind power can increase my immune system. When people get sick in flu season, is it because of the real flu, or because of the psychological effect? Just because workmates around me got sick, doesn't suggest I will be ill likely, right? Does our mind play a role in this? What's your thought on this?

Stay healthy and strong everybody!
blessing,
Xing