Great comment from "J" I am reposting here:
When I first started studying Epicurus, I was very much afraid of death. Every time I found myself worrying about my future demise, I could calm myself by reading the third paragraph of the Letter to Menoeceus – which is the argument you presented. It clearly addressed the source of my fear, because I would always feel better after reading it. I memorized the paragraph, because I knew that I wouldn’t always have a copy of the letter readily available. Over the course of a few months, my fear of death disappeared. Off topic, but an important point I want to make – cultivation of these concepts is important. Although they may make sense the first time you read them, it doesn’t mean that you have absorbed it and that it will be available to you when you need to apply it. There are also concepts that I have not understood the first time I read about them. But if I read them over and over I started to understand them. I believe this is why Epicurus stressed memorization so much. I highly recommend that you memorize any PDs, Vatican Sayings, paragraphs from the letters etc. that address the issues that are most important to you, even if you don’t fully understand them yet. By doing so, you will come to understand them at the core of your being.
The above story addresses the argument that death is nothing to us, but the counter arguments that you mention are not addressed by this. The counter arguments touch on the concept of infinite time versus finite time and length of life in general. The corresponding teachings that relate to this are:
PD 19: If we measure the limits of pleasure by reason, infinite and finite time both provide the opportunity for complete pleasure.
PD 20: We assume that physical pleasure is unlimited and that unlimited time is required to procure it. But through understanding the natural goals and limits of the body and by dissolving the fear of eternity we produce a complete life that has no need of infinite time. The wise man neither flees enjoyment, nor when events cause him to exit from life does he look back as though he had missed any essential aspect of life.
Epicurus also mentions it in the Letter to Menoeceus (DeWitt translation): “But the multitude of men at one time shun death as the greatest of evils and at another time choose death as an escape from the evils of life. The wise man, however, neither asks quarter of life nor has he any fear of not living, for he has no fault to find with life nor does he think it any evil to be out of it. Just as in the case of food, he does not always choose the largest portion but rather the most enjoyable; so with time, he does not pick the longest span of it, but the most enjoyable.”
Now, reading these things does not have the same effect for me that reading the third paragraph of LTM had on my fear of death, but I had a neat experience recently that suggests to me that simply by studying Epicurus these things will start to make sense even if I don’t completely understand it at first.
I used to tell people that I was going to live to 104. Very recently – like just a couple of weeks ago – a situation came up where I would normally say “Well, I’m going to live to be 104,” but to my surprise it didn’t feel right to say anymore and I realized that I no longer felt the need to live that long. I am not saying that I don’t think I will live that long – I might. What I am saying is that my desire to live to 104 stemmed from this belief that a longer life is somehow better and that my feelings about this somehow shifted without my working on it. For some reason, I seem to understand at my core that the length of my life is not important. What is important is that I now know that complete pleasure is possible and that I am getting closer to it. The more I study Epicurus, the closer I feel I am getting to experiencing complete pleasure. Right now, the biggest thing I am doing to get closer to complete pleasure is exactly what Elli mentioned – I am dispelling desires that stem from vain imagination. Perhaps the idea that a longer life is better than a shorter life is itself a product of vain imagination, but I think it is one that is difficult if not impossible to dispel directly. As I shed other vain desires this one seems to weaken for me as well. So perhaps this paragraph from LTM would be a good one to memorize too (DeWitt translation):
“As to the desires, we must reflect that some are natural and some are imaginary; and of the natural desires some are necessary and some are natural only; and of the necessary desires some are necessary to happiness [he refers to friendship], and others to the comfort of the body [clothing and housing], and others to life itself [hunger and thirst].
“Because a correct appraisal of the desires enables us to refer every decision to choose or to avoid to the test of the health of the body and the tranquility of the soul, for this is the objective of the happy life. For to this end we do everything, that we may feel neither pain nor fear. When once this boon is in our possession, every tumult of the soul is stilled, the creature having nothing to work forward to as something lacking or something additional to seek whereby the good of the soul and the body shall arrive at fullness. For only then have we need of pleasure when from the absence of pleasure we feel pain; and conversely, when we no longer feel pain we no longer feel need of pleasure.”
My apologies for the novel and thanks to anyone who read it. 
