A trick perhaps. But one that may help when need is at its peak. Thoughts can not be easily dismissed, but they may be replaced. You do it with the hands. You are not your thoughts.
Thoughts are like clouds, some light and fluffy, others dark and menacing.
You, however, are the sky. When the clouds are dark and menacing. When there is fear and anxiety. When there is depression and hopelessness. Enough to see them, but not enough to stretch the muscles.