Nothing will make up for his past mistakes.
The situation allows of no delay.
I want you to see to it that everything goes smoothly.
It's best to err on the side of prudence.
We cannot afford to ignore the lessons of the past.
Will he overcome the bitterness of the past?
Once he had made that devastating remark, the matter was completely past mending, past recall.
You should not look back to the past.
It's nothing to make a great fuss [a song and dance] about.
I'm reflecting upon my immature deeds.
Things were screwed up from start to finish.
Don't worry about the past.
Complaining won't get you anywhere.