Fear is actually the mentally passing through (giving attention and experiencing virtually) the states in which you could end up if you were to perform a certain act. When deciding, you always try to find out the possible consequences of each choice option. During this feedforward activity, to be on the safe side, you also check the different scenarios of how the things you don't control can influence those consequences. In this contingency (eventualities) study you let your likes and dislikes that would be triggered by certain consequences if they would actually happen, actually determine which options are acceptable for you, and which ones are not at all. So it's an excellent mechanism because you're more likely to be in the shit than you get out of it. That's why: Fear regulates the heartbeat of feedforward. Fear is worth its weight in gold. But dealing with it can also be quite unpleasant. And this is why (= pdf).