"Don't look back; you're not going that way."
Social media loves wisdom memes like this. And this is a good one, so far as it goes.
The apostle Paul said, "But one thing I do: forgetting what lies behind and straining forward to what lies ahead, I press on toward the goal for the prize of the upward call of God in Christ Jesus (Phil. 3.13b)
....forgetting what lies behind...." he says after spending the preceding paragraph recounting all the things in his past he was once proud of. He hasn't forgotten anything.
Paul is talking about a forgetting in different way, a way that fully understands the import of the past, that clings to the truth of it and the wisdom gained from it, but leaves behind its vanity, foolishness, and sin.
“...then take care lest you forget the Lord, who brought you out of the land of Egypt, out of the house of slavery.” Deut. 6:12
Wisdom looks back and remembers the faithfulness and mercy of God it has already experienced. It looks back and remembers past mistakes and sins so as not to repeat them. It looks back to remember the upward call of God.
Wisdom doesn't see today as a moment disconnected from all days past and future. It doesn't see it disappearing into nothing. It sees every today is the yesterday on which tomorrow is built. Wisdom ensures that today is not wasted.