By giving a counter suggestion that nothing will go wrong and repeating to yourself an inspiring phrase such as ‘all will be well’ or a mantra that makes you feel connected with God.
At the same time one should also reason it out by reminding oneself that we often attract what we fear.
One can also the imagination and throw in positive auto suggestions as well as imagine a beautiful white light dissolving the negative thought and making it melt away.
Affectionately,
Alok da.