I assume it's not a good idea to exercise when one has a cold. What are your thoughts on this?
Great question! When you are sick, you need to pay careful attention to what your body is telling you. If the cold is primarily in your head, it's OK to exercise, just at a lower intensity (provided you feel OK and have enough energy). Once you are feeling 100% again, then you can slowly increase your activity back to your pre-illness level. If you're feeling sluggish or the workout isn't going well, don't push it. When you push too much, the sickness can end up hanging around longer.
If your cold is below the neck (in your chest), try to refrain from activity until it clears up. The best thing you can do for your body when it's trying to fight a bug is to give it rest.
Exercise Extra: Regular exercise strengthens your immune system, so you'll get sick less often and usually recover from an illness more quickly