A stoic response to fear and worry would be that it is not very fruitful. Seneca implores us in his letter to his friend, Lucillus, to value time above all else, as it is the most precious and non-renewable resource we have:
What man can you show me who places any value on his time, who reckons the worth of each day, who understands that he is dying daily? For we are mistaken when we look forward to death; the major portion of death has already passed. Whatever years be behind us are in death’s hands.
Therefore, Lucilius, do as you write me that you are doing: hold every hour in your grasp. Lay hold of to-day’s task, and you will not need to depend so much upon to-morrow’s.
Marcus Aurelius in his Meditations, states:
Though thou shouldst be going to live three thousand years, and as many times ten thousand years, still remember that no man loses any other life than this which he now lives, nor lives any other than thiswhich he now loses. The longest and shortest are thus brought to the same. For the present is the same to all, though that which perishes is not the same; and so that which is lost appears to be a mere moment. For a man cannot lose either the past or the future: for what a man has not, how can any one take this from him? These two things then thou must bear inmind; the one, that all things from eternity are of like forms and come round in a circle, and that it makes no difference whether a man shall see the same things during a hundred years or two hundred, or an infinite time; and the second, that the longest liver and he who will die soonest lose just the same. For the present is the only thing of which a man can be deprived, if it is true that this is the only thing which he has, and that a man cannot lose a thing if he has it not.
This phrase especially bears repeating as it is very poignant and real: