It's pretty hard to breathe when you have constant mucus flowing back and fourth to your nose and the back of your throat. The sinus pains hurting the back of your eyes is no fun either. You don't even notice when its laced with adrenaline though, I go running with colds all the time especially since Mass's weather is so off key. But it's still an impediment. Old news though, but some people don't mind hearing that kinda junk.