Following I quote excerpts from A Course in Miracles, which, I feel, are some of the clearest thinking on the roots, the nature, and the solutions of fear.

"Fear of [Truth] is one of the strangest beliefs the human mind has ever made.  It could not possibly have occurred unless the mind were profoundly split, making it possible for it to be afraid of what it really is.  Reality cannot 'threaten' anything except illusions, since reality can only uphold truth.  The very fact that [Truth], which is what you are, is perceived as fearful, demonstrates that you are afraid of what you are.  It is not, then, the [Truth] of which you are afraid, but of your...[truth].

"...What seems to be the fear of [Truth] is really the fear of your own reality.  It is impossible to learn anything consistently in a state of panic.  If the purpose...is to help you remember what you are, and if you believe that what you are is fearful, then it must follow that you will not learn....yet you do not know what you are.

"If you do not know what your reality is, why would you be so sure that it is fearful?  The association of truth and fear, which would be highly artificial at most, is particularly inappropriate in the minds of those who do not know what truth is.  All this could mean is that you are arbitrarily associating something beyond your awareness with something you do not want.  It is evident, then, that you are judging something of which you are totally unaware.  You have set up this strange situation so that it is impossible to escape from it without a Guide Who does know what your reality is.  The purpose of this Guide is merely to remind you of what you want....

"You have imprisoned your will beyond you own awareness, where it remains, but cannot help you....[Wisdom's] function is to sort out the true from the false in your mind....[It's] recognition of [Truth] can make it real to you, because [It] is in your mind, and therefore [It] is your reality....[It] is helping you to remember what you are.  The only source of fear in this process is what you think you will lose.  Yet it is only what [Wisdom] sees that you can possibly have.

"...[Wisdom] will never call upon you to sacrifice anything.  But if you ask the sacrifice of reality of yourself, [Wisdom] must remind you that this in not...your...[will].

"....How sensible can your message be, when you ask for what yo do not want?  Yet as long as you are afraid of your will, that is precisely what you are asking for.

"You may insist that [Wisdom] does not answer you, but it might be wiser to consider the kind of questioner you are.  You do not ask only for what you want.  This is because you are afraid you might receive it, and you would.  That is why you persist in asking the teacher who could not possibly give you what you want.  Of him you can never learn what it is, and this gives you the illusion of safety.  Yet you cannot be safe from truth, but only in truth.  Reality is the only safety.  Your will is your [healing] because it is the same as [Wisdom's].  The separation is nothing more than the belief that it is different.

"...no one really wants either abandonment or retaliation, even though many may seek both.  Can you ask [Wisdom] for 'gifts' such as these and actually expect to receive them?  [It] cannot give you something you do not want.  When you ask the Universal Giver for what you do not want, you are asking for what cannot be given, because it was never created.  It was never created because it was never your will for you.

"....In the presence of truth, there are no unbelievers and no sacrifices.  In the security of reality, fear is totally meaningless.  To deny what is can only seem to be fearful.  Fear cannot be real without a cause, and [Life] is the only cause.  [Life] is love, and you do want [It].  This is your will.  Ask for this and you will be answered, because you will be asking only for what belongs to you.

"When you ask [Wisdom] for what would hurt you [It] cannot answer because nothing can hurt you, and so you are asking for nothing.  Any wish that stems from the ego is a wish for nothing, and to ask for it is not a request.  It is merely a denial in the form of a request.

"You do not recognize the enormous waste of energy you expend in denying truth.  What would you say of someone who persists in attempting the impossible, believing that to achieve it is to succeed?  The belief that you must have the impossible in order to be happy is totally at variance with the principle of creation.  [Life] would not will that happiness depended on what you could never have.  The fact that [Life] is Love does not require belief, but it does require acceptance.  It is indeed possible for you to deny facts, although it is impossible for you to change them....If you deny love, you will not know it because your cooperation is the law of its being.  You cannot change laws you did not make, and the laws of happiness were created for you, not by you.

"Any attempt to deny what is must be fearful, and if the attempt is strong it will induce panic.  Willing against reality, though impossible, can be made into a very persistent goal even though you do not want it.  But consider the result of this strange decision.  You are devoting your mind to what you do not want.  How real can this devotion be?  If you do not want it, it was never created.  If it were never created, it is nothing.  Can you really devote yourself to nothing?

"....You cannot distort reality and know what it is.  And if you do distort reality you will experience anxiety, depression, and ultimately panic, because you are trying to make yourself unreal.  When you feel these things, do not try to look beyond yourself for truth, for truth can only be within you."