I don't find fear to be very useful most of the time:

 Of course there are always exceptions to this rule like when you are standing on the edge of a cliff there is a tendency in most people to contemplate jumping. At times like this, fear might be useful just like when a bus or huge truck is bearing down on you when you are crossing a highway on foot. Fear might be useful if it gets you out of the way of dying by truck or bus that doesn't see you.

But, generally speaking being afraid appears to me to be counterproductive. What is more important is to be level headed and logical and reasonable no matter what happens.

For example, when ships sank during battles for thousands of years it was usually the older sailors (over say 25 or 30 who survived). Why?

Because it has to do with experience in life. If you are younger you haven't survived that much yet and people haven't tried to kill you that much yet so when your ship sinks and you don't have a boat to survive in you might panic or die from getting too upset. But, if you are older you have already survived so many attempts on your life of various kinds that you know to be circumspect and calm because it is the only way you have any chance of surviving your ship sinking without a lifeboat.

Another interesting thing is that bellbottom trousers were on sailors for a long time because they can be turned into life preservers in an emergency when ships sank. If you take off your pants and fill them with air the water in the weave holds the air somewhat and keeps you potentially alive much longer if you are on a ship that sinks at sea thereby increasing your chances for survival.

The way I presently understand it is you take off your bellbottoms in the water and tie two knots where the pant legs connect to the groin area of your pants then you fill the two pant legs with air to stay afloat.This is also why sailors bell bottom trousers were usually made of a very thick weave or fine weave to better hold air when wet to increase flotation times.