Here are two of my favorite early entries from Soren Kierkegaard’s Journals & Papers.
I will not lament the past – why lament? I will work energetically and not waste time in regrets, like the person stuck in a bog and first calculating how far he has sunk without recognizing that during the time he spends on that he is sinking still deeper. I will hurry along the path I have found and shout to everyone I meet: Do not look back as Lot’s wife did, but remember that we are struggling up a hill.
Philosophy is perfectly right in saying that life must be understood backward. But then one forgets the other clause – that it must be lived forward. The more one thinks through this clause, the more one concludes that life in temporality never becomes properly understandable, simply because never at any time does one get perfect repose to take a stance – backward.