Getting a cold actually shows your immune system is in working order, when you stop getting colds you should worry, because your immune system isn't recognizing pathogens!
The people who say I never get sick-never catch colds or the flu are the ones who have the weak immune systems!
Cold symptoms, such as, runny nose, fever, cough... are the body's way of "naturally" clearing out pathogens, when this no longer happens you are in trouble.