It's easy to say - don't panic. But how do you stop panicking? I think you need to learn to calculate your actions in advance and try to avoid stressful situations.
Yes. So in our family the "Don't panic" is a trigger for pre-defined follow-up actions. It isn't a corrective phrase, it is the start of a series.
For the trading, you should have a safety trigger set up to stop the spiral :)