Well, over the years, I have learned a few things. With some thing minor, like a cold, I keep up my training. If nothing else, it clears up my sinus's. For some thing more serious like the flu, I will slow down for a bit, then when I am past the main part and on the down/healing side, I ramp up my work outs. My theory is that most virus's don't have much tolerance for temperature variations, and the extra heat burns them up, or out in the case of when you are starting to recover.
