We should not fret for what is past, nor should we be anxious about the future; men of discernment deal only with the present moment.

Do not dwell in the past, do not dream of the future, concentrate the mind on the present moment.

If it’s over, then don’t let the past screw up the rest of your life.

Chronocanine Envy:
Sadness experienced when one realized that, unlike one's dog, one cannot live only in the present tense. As Kierkegaard said, "Life must be lived forward.

Nothing is but what is now

You can always cope with the present moment, but you cannot cope with something that is only a mind projection - you cannot cope with the future.