&gt; Anecdotal, sure, but either the illness or the cure was in my head.<p>A powerful thought is that your entire life experience is in your head --- your nerves relay signals from throughout your body, but it&#x27;s up to your brain to interpret them, and you can change the interpretation. Some conditions can get better if you reinterpret their signals. Some conditions can get better if you relax because you feel in control. That&#x27;s not to say you shouldn&#x27;t take appropriate medical steps, too, I&#x27;m sure there are some things to check for with mystery vomiting, for example, but then you run out of things to check.