Is Picard asking about addressing fear in general in a highly stressful situation, or is he asking about having a panic attack specifically?

From the Mayo clinic: "A panic attack is a sudden episode of intense fear that triggers severe physical reactions when there is no real danger or apparent cause. Panic attacks can be very frightening. When panic attacks occur, you might think you're losing control, having a heart attack or even dying." It is a medical condition that can be treated. <http://www.mayoclinic.com/health/panic-attacks/DS00338>

If we're just talking about handling stressful situations better, then, yes, train regularly in a stressful task. This will take commitment, because, whatever activity you're training in needs to be safe -- or safe enough, because it should have some real risks. To manage risks well, you need to start small, gain skill, and gradually tackle bigger and bigger problems. One way to do it is through a good martial arts place with a strong practical focus -- and that includes developing the "fighting spirit," which means the proper psychology to get you through a violent conflict. I'd think sports that involve an element of danger and a lot of skill will help, too -- rock climbing, for example.

Also, it helps to train for the situation you want to be prepare for. So when you find yourself in the situation, you can just follow a pre-programed flowchart. You have something to do, something to focus on, so you won't give play to the fear inside of you screaming to get out.

There has been some discussion on this sort of stuff. I think it was Night Hiker who said he found it helpful to focus on the immediate tasks rather than on the big picture, and that was how he got out of an up-side-down submerged helicopter. That seems like a good tip.