It is very difficult, sometimes, to avoid being gripped by fear - and by 'fear' I do not mean that acute emotion which leads to adaptive behaviours such as 'fight or flight'; but that chronic existential fear (or 'angst') which gets hold of the emotions, distorts thinking, and Will Not Let Go.
It is important to recognize that such fear is a sin.
It is a sin because it is is a consequence of lack of faith (i.e. lack of trust, lack of confidence...) in the goodness, love and creative power of God; and the salvation of Jesus Christ.
And sin itself is - in its deepest meaning - death (including that which conduces Men to choose death). That is, death as understood as the severance of the (eternal) soul from the (dead) body; with consequent loss of our agency, our consciousness of our-selves - so that we would become witless, demented, discarnate 'ghosts'. When Jesus offered the possibility of saving Men from 'sin' - it was this condition from which he was saving Men.
There are always causes for fear; and fear may (it seems) strike anyone. I have read many accounts of World War One pilots, that make clear that the most courageous people one can imagine - men who have risked death, three times a day for months on end, in single combat with superior enemy forces - can, and eventually will experience, paralyzing fear.
And such fear of death can be so extreme and unbearable, as itself to lead to either deliberate, or semi-deliberate, seeking of death - death to 'put an end to' (as it seems) the fear of death.
But even in what is apparently the safest and most secure individual lives - perhaps especially in such lives - there may be an intense dread of losing safety and security.
Thus, fear is part of the human condition.
If so, if sin is unavoidable - how can it be sin? And how can sin be overcome if it is part of the human condition?
Well - sin is part of the human condition; and sin cannot be overcome fully and finally in this mortal life on earth...
But this inevitability of failure does not matter in the ultimate scheme of things, since this mortal life on earth is intended as a time of learning and preparation, a time of tests and opportunities - the benefits of which learning may be 'enjoyed' through eternity (in resurrected Heavenly life), as well as providing glimpses and hope for that eternity.
The inevitability of fear is, in a sense, liberating! Because it diminishes the delusory hope of avoiding fear, and puts the emphasis on what we do when we fear.
In sum: fear cannot be avoided, it will always come back again - and again; but fear can be dealt with when it does return.
Fear can be dealt with every time it returns, no matter how many times it returns - and it is this dealing-with fear that is what does us good...
And does us good, not here in this mortal life on earth; but good ultimately and eternally.
This way of understanding sin (which, in my case, derives-from a close reading of the Fourth Gospel) is liberating, and hope-full; since it is attainable by anyone; even (perhaps especially) those most prone to fear.
Each experience of fear is an occasion for recognizing that it arises only from the weakness of our faith; and repenting that fact. That is: recognizing that our existential angst about 'the future', about what might or will happen - is a sin arising from the mortal inadequacy of that confidence and hope which ought to come from our belief in God and following of Jesus.
It is such 'knowing and affirming what is right' that constitutes repentance.
Such a perspective (albeit temporarily achieved) may provide some here-and-now relief (albeit temporary) from the fear that afflicts us. It may stop such fear from getting worse, rather than (as otherwise usually happens) feeding upon itself.
But even if no relief is obtained, even when we cannot 'make ourselves' feel the love of God and Jesus we know we ought to feel; the very act of repentance is valuable - permanently valuable.
It is this knowing what is right, and wanting-to-want what is right, that is most important.