It is especially a feature of Old Age (from the early fifties, typically) that some have a strong memory while others forget - some live in the past, others in the now.
I believe that those who survive to old age do so for a reason - they are sustained by God to learn something important to them.
Crudely put, to acknowledge and repent their sins, but perhaps a particular sin which threatens salvation - which may provoke them to reject resurrection and Heaven, to refuse to follow Jesus after death.
Everybody who is alive, remains alive for Reasons - and these reasons are spiritual, and these reasons shape our situation.
One who has a strong memory and lives in the past probably has something in need of acknowledging and repenting. Not to feel Guilt for sin (feeling which is akin to fear and itself a sin indicating lack of faith), but to recognise, and ask God for forgiveness.
One who forgets, and whose disposition is to live in present and future, might need to examine motivations.
One whose drive diminishes and motivations dwindle, may be being encouraged to set aside hopes placed in worldly plans and schemes.
in sum, our actual situation and condition are shaped by The Creator so that we have the best possible chance to learn what we most need - need Spiritually.
We Are Alive for reasons, all of us - and learning the reasons is a vital aspect of why we are still alive.
