In one of my "toilet inspiration moments", it became clear to me.
There is no point in moaning and groaning about the past, because it has passed. Nothing can change it (unless time travel becomes possible but that's another story in itself).
The only thing we can do is to look forward, and walk. To walk and walk and continue walking till the end. Look in front. Look far into the horizon. Look far away till your eyes can't see. That's where we are aiming for.
So go. And don't turn back. Just go.