While their training was rigorous and thorough, the way in which Navy SEALs were historically trained didn't prepare them to deal effectively with uncertainty and stress. So now, they follow these steps:
Before the event
The first step involves visualizing your objective, seeing an upcoming meeting or situation and imagining the factors critical to success. Break down your objective into small, manageable tasks.
Next, visualize a positive outcome. If it's a new appointment, see all the positive steps you want to take. Even if it's a difficult meeting, imagine what a positive outcome would look like. Whatever the situation, this step is crucial.
During the event
This step requires you to make a positive internal affirmation. Tell yourself "I am totally capable of doing this" or "I am well prepared to handle this situation." The best affirmation is the one that works for you. This affirmation won't take long to repeat internally; research has shown we speak to ourselves at a rate of 300-1000 words per minute.
The next step involves breathing. To settle yourself, take a few deep breaths before you begin. Repeat this step as necessary. The goal of these first four steps is to help you prepare for and stay present in any situation.