I rarely get a cold, but when I do, it completely and utterly destroys me for what feels like forever.
I tend to try to continue living my life as normal, and then drink a bunch of tea. I think that my complete and utter ignorance of the fact I'm run down is probably the reason that it lasts so long. I'm sure that if I yielded to it, I would get over it faster, but life stops for no one. As long as I can move, I'm moving.