I once knew a very wise woman who, being of advanced age, chose to pass on some advice.
She said that once a year, she would write in a journal what she'd learned about life. The lessons were not confined to what had happened in the past twelve months. Sometimes, she would discover an insight into a matter that she'd pondered for years.
Since I was quite young and very busy, I muttered some cautious response about the idea being interesting and then went on with my life.
As I grew older, her advice kept returning. I recall her noting that she would review her previous entries to see how her views had changed. That too is a treasure I failed to preserve although I'm certain that such a review would be humbling indeed.
Much of life is rediscovering lessons that we once thought would be unforgettable. Another portion is revising ones we regarded as solidly grounded. We so often tackle those tasks in a haphazard manner. For a very long life, she was addressing them systematically.
I have no doubt that she gained far more than those of us who use a less disciplined approach.