I think you're on the wrong track. It's been over 6 years since I've been sick. I also eat really well. Too much stress compromises the immune system, sure. Of

I think you're on the wrong track. It's been over 6 years since I've been sick. I also eat really well. Too much stress compromises the immune system, sure. Of course. And for many people, running a marathon constitutes that threshold of too much stress. I haven't felt that. Perhaps doing a 100-mile mountain race would, though...