Fear and not knowing go hand and hand. You can check this out for yourself. The next time you are afraid about something, look and see if it is because you don't know what is going to happen or you are certain you know what is going to happen...do you see that you actually don't know, however, you fear that you do know.
Fear thrives on the past and the future but cannot exist in the now. Instinctual/body fear yes...but emotional fear, cannot. All one has to do is bring the attention back to the present moment to see that this is true. In the present moment is the fear/worry/concern that you are experiencing actually happening or are you only thinking about it happening? Is it right in front of you? Can you touch it? Can you smell it? If you can't then it is not happening and it is a lie.
Sometimes it takes a lot of reminding oneself that all psychological fears, worries and concerns are just distractions from the present moment which is Peace, real Peace, not the peace that comes and goes depending on a situation, but the Peace that passes understanding. The closer one gets to the present moment, the more Aware one becomes of the Peace that they are in.
These are not things that can be given to you, you have to investigate for yourself. Again, the way to investigate is to just stop. Whatever you are doing just stop. Take a look around you. A slow, calm, look around you. Is there anything actually happening? Is anything that you are thinking actually happening? If it is then be afraid. If it isn't ... have a smile.