+1.
I had the flu over Thanksgiving which involved a terrible sinus infection which then turned into a chest cold. After three weeks I thought I was well enough to start riding to work again, but I ended up setting myself back.
This season's cold seems to be especially tenacious.
Like five one, I have a history of asthma and my doctor gave me a fresh inhaler prescription to help keep the lung congestion in check. She also suggested that I should dial back on the physical activity until the cold clears up, particularly outside.
I've told myself that I'll stay off my bike while the weather is cold. Something about the cold and staying warm and being able to regulate my body temperature. I'm still doing some light indoor exercise. Pilates, some of my old PT routine to keep up my muscle tone around the parts of my body that have a history of trouble, and if I want to get my heart rate up I'll play a little Wii Tennis or Boxing. It's not where I'd like to be physically, but at least it keeps the muscles from stiffening up.
This is probably not for everyone, especially if your symptoms are severe, but I've done a couple of sauna sessions this past week and that also seems to have helped. I don't think the virus likes those higher temperatures.