I assume here that there is indeed a spiritual role for old age, and that ageing is not merely decline: that fact that God maintains someone alive, means that person has work of spiritual importance to be done.
In the first place there is the chance for salvation, and secondly for spiritual progression towards higher consciousness (i.e. to make conscious and freely-choose those Goods which were previously unconscious and spontaneous).
But these are personal spiritual jobs; and we are not isolated Beings but are some part of networks of love (love of 'neighbours' as the Gospels call it).
Therefore, as well as personal or private work - old Age also has a task of 'social' or 'public' spiritual work to do.
In other words; in Old Age each person has spiritual work to do for the general benefit.
What seems to happen is that the material for such work comes to mind spontaneously; but the work itself requires agency.
What we need to work-on will come to mind without specific effort; but the positive spiritual work that needs doing requires discernment and right-choices; and, as usual, there are temptations (wrong choices) that point in harmful and evil directions.
In old age; attention naturally tends to switch from the present and future towards the past. Thus, it is a true stereotype of old age that certain 'memories' or themes recur; and the old person tends to go over-and-over events from his past (privately, and perhaps in conversation).
Places, people, events, past decisions... these are examples of the kind of things that recur.
They may recur by being reminded of them in everyday life, coming to mind in reflection or daydreaming, or in actual dreams.
A particular thing may be the one subject of recurrent interest; and there may be a few - or many and changing things. This difference depends on what the individual most needs to do, and is capable of doing.
Interest in these themes is spontaneous; but may be sustained or brief. Which happens in a particular person will depend on the individual's needs and capabilities. Some people need to work hard on one matter; while another person may need to survey many things - and become aware of their implications.
These form the material of spiritual activity; and the task is to work on this material in the proper way - which is spiritual and inner rather than physical and outer; and with proper aims - which are directed at spiritual outcomes in eternal resurrected life, rather than material outcomes in this mortal life.
Although the material appears as 'memories'; ultimately what is being worked-on is not what modern society regards as memories. Instead, what is being worked-on are past realities that survive in present creation - survive in the thinking of active Beings...
What come to mind is (presumably) shaped by our personal needs - as ascertained by that-which-is-divine in each Man; in the context of being in harmony with the aims and loving-nature of divine creation, as shaped by the Holy Ghost.
In other words - we are given as material not only what is important to our salvation and spiritual development, but also what is important to other beings in ongoing divine creation. And 'important' is here understood in terms of post-mortal, resurrected and eternal life - not by the temporary and material aspects of this mortal and earthly life.
The process of working-on these 'memories' is therefore not in terms of public use, and does not need to be communicated to other people. It is a matter of having the right kind of thoughts, not about saying (nor doing) the right kind of things.
The 'right kind of thoughts' involve things like becoming aware of that which was unconscious, re-evaluating that which was misunderstood, grasping the wider context of that which was seen in isolation.
In generic terms; we are called-upon to bring-to awareness from our own unique personal perspective things of the past; and to create new understandings, and to make new links and contexts.
In sum, this is creative work: it is the work of changing and enhancing divine creation; by, in effect, picking-up unfinished or wrongly-understood business for our past and knowledge; and making new and better understandings, adding meanings, and making relationships... All guided by the aims and (loving-) methods of divine creation.
It is work that only we our-selves can do; because our nature and perspective is unique. If we, personally, do not do this work: then it will not be done, and creation will be otherwise than it would have been.
Therefore, old age is not meant to be passive and reactive merely; there is work to be done - but spiritual not physical work, and not necessarily involving other people in material terms.
That work will come to mind spontaneously; and then the active job is to review, consider, evaluated, contextualize that material - in a spirit of love.
To emphasize: the work itself is not automatic - the process of working must be chosen, and choices need to be active.
And there are many potential temptations that can derail the work from its proper aims, methods and conclusions; and lead to harm instead of benefit.
Indeed; it would seem that most old people nowadays fall prey to one or more of these temptations, and end by doing spiritual harm to themselves - and failing to benefit their 'neighbours'.
For example; they may react wrongly, in the wrong spirit, to the material brought up by memories. In the first place, they may regard the whole business as physical, not spiritual; and earthly not eternal.
Some people may brood resentfully and recurrently on (real or imagined) past wrongs done to them; others engage in wishful thinking and vain regrets - that they had, or had not, done some-thing (which they suppose would have then made their past or present lives better).
Others may cycle and re-cycle remembered material superficially or verbatim - over-and-again but without ever bring to consciousness new aspects, or striving to learn from it.
Or people may use past memories with an aim to ameliorate or improve present mortal life; perhaps by trying to attain higher status through memories of self-aggrandizement; or by seeking excuses/ rationalizations for present sins.
Another spiritual mistake is simply to regard memories as nothing more than opportunities for pleasurable reminiscence; merely a chance for feeling better here-and-now, and passing the time pleasantly.
So there are innumerable ways of derailing the task of old age; but also there is real and valuable work potentially to be done. And so long as God maintains us alive, the old can choose to do this work.