[rationalist]

Your statement can have multiple interpretations. I assume you mean this one: Your fear will be a self-fulfilling prophecy; to prevent that, stop being afraid?

Of course that's like telling someone who is depressed, to "just be happy".

[buddhistdude]

I think he means that thoughts have an actual effect on the unfolding of the physical world.

[rationalist]

Which is a "self-fulfilling prophecy", also known by a new-age term as "manifestation".