We'd all probably prefer if gym goers feeling under the weather kept themselves and their germs far from the treadmill and shared yoga mats. The sniffly and sick, however, often can't stay away. But are they doing more harm to their bodies than good? This Cox News Service article, written by a certified trainer, says if you have a fever, symptoms below the neck or a hacking cough, exercise could further stress your immune system. If the trainer says to skip a workout, you've got a pretty good excuse for staying home.