Panic asks what could go wrong; composure asks what must happen next.

Panic runs a survey of everything that could go badly, which is unlimited and produces no action. Composure asks a much narrower question about the next required step, which is answerable and leads somewhere. Both feel like engaging with the problem, and only one of them moves.

When your mind starts generating disaster scenarios, redirect it to the immediate next action. Just the one. Answering that question repeatedly gets you through the situation, whereas answering the other question has no end.