The bigger the crisis, the calmer you get. Becoming emotional will lead you to make rash, impulsive decisions. Your teams and your customers will feed off your energy.
In any setback, first determine how much of the damage was self-inflicted and how much was because of the market. Look around at who else stumbled, and why they did. Look at the numbers but talk to the people behind them: your employees, your suppliers, your peers, and most important, your customers.