Fear can be a good servant. For example it will remind you to keep your gun in your pants if you don’t intend to shoot or to keep it on your body (close) rather than getting it in front of you and hiding behind it (you choose what to fear from and in this case, loosing the gun) Fear and pain will remind you to protect your head when you get up in a low visibility location like underground or if you have a head injury and cannot see well. Fear reminds you to get yourself out of the way of a strike and most of all to look for the next target as you work.