I know that this superstition is pretty common with OCD. I have it all of the time. I think that thinking something or saying something a certain way will jinx myself (even if I didn't intend it or it's done accidentally), and it causes a spike in my anxiety, and I start to panic about it. It's common with health anxiety too because it takes on many OCD-like forms.
It's something I struggled with for a while, but I've gotten better at combating it. You just have to remind yourself that it's not the way the world works, and it's your disorder convincing you that you almost have "powers." Think about it, if that were really true, and your thoughts could control the outcome, I think a lot of us wouldn't have health anxiety anymore for as often as we wish we didn't have it, right?