People's perception of the effect of stress on their health is linked to risk of heart attacks
This is a great example of the nocebo effect, which is the evil cousin of the placebo effect. As we all know, a placebo effect is when you experience a presumed benefit from an inert material simply because you don't know it is inert, but instead think it to be an active compound... the old "sugar pill" in the drug trial. But what happens if you believe the sugar pill is actually something that is bad for you? As it turns out, things that have no effect could harm you if you believe they are harmful, or things that are only a little harmful could be made worse by your perception, as is the case here. So don't stress about the stress... you're only going to make it worse.