If you try to work out much when tired and stressed you're just going to increase the odds of getting sick. The article makes the mistake of suggesting exercise

If you try to work out much when tired and stressed you're just going to increase the odds of getting sick. The article makes the mistake of suggesting exercise when already stressed. I think the point here is that fitness is protective. It's too late if you're already feeling a bit burned out. The thing to do in that case is restful relaxation.