Acceptance of what is now and what has gone on before without attachment or emotional involvement is, in my view, a critical success factor in the maintenance of a sound mind.
One is not able to change what has gone on before, it is done. One is not able to change the here and now, it is present.
The present has unfolded, like a flower, from the seeds sown in the past.
What one can do is to sow the seeds that may develop into their own flowers.
My model here is that the calm acceptance of what has gone on before and what is here now is provides a crucial element in establishing the best frame of mind for deciding which seeds we sow.