"It's very simple. As you grow, your immunity grows too. But so also do the microbes that want to damage your immune system.", said the professor.

 

"That's no reason to want to take a shot in the arm when you are a big adult.", said the student.

 

"It so happens that some microbes target specific targets, especially those who have it in their life-stories.", said the professor.

 

"Do you mean to say that we attract those microbes?", asked another student.

 

"Ah...yes, to some extent. We create the life-story and also attract the characters into it. We just need to be sure that the malignant ones are left out hanging in the imagination and beneficient ones enter when it comes to actually living out the story."