We are often told not to regret past events, that there's nothing we can do now, considering what's already been done. However, we are also told that we can learn from the past and become better people. By reflecting on our wrongdoings and improving on them, we can do better in the future. So what should we do?
First of all, it is good for the mind not to think any more if we suffer from the mistakes or unavoidable circumstances of the past, or if we scold ourselves too much. If you're struggling with what's already done and can't concentrate on your work, it's better to send the past neatly away.
However, there is certainly something to learn from the past. Just as we learn through history, we should develop ourselves through past cases. A certain amount of reflection can work to improve us, but as I said before, make sure you are not too tied to being hard on yourself that it hurts you.
Just like the title of the old British band, Don't Look Back In Anger.