I once read a report saying that elderly people were more optimistic about the future than younger people were.  Maybe part of the reason is there will be less time left for old people than for younger.  But that does not explain it fully.  I believe that experiences we have throughout our lives prove that most of the difficulties we have in our lives are not that bad compared to what  we usually predict beforehand, and there have been ways to overcome those troubles beyond our expectations.
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