British historian and writer James Howell first used this phrase in one of his books in 1659. It means that there is no use in being upset over past events that have already happened and cannot be undone. The same sentiments are expressed in the Mahabharata. It says that once Devrishi Narada visited Shuka, the scholarly son of Rishi Vedavyasa. Shuka requested Narada to give him knowledge that would be beneficial for him. Narada gave him some tips about how to dispel grief and attain happiness.
He said: Shokasthanasahastrani bhayasthanashatani cha, Diwase diwase mudhmavinshanti na panditam.
From day to day, a thousand causes of sorrow and a hundred causes of fear afflict one that lacks understanding, but not one that is possessed of wisdom and learning.
Narada further said: Mritam va yadi va nashtam yoateetmanushochati, Dukhen labhate dukh dvavanarthau parapyate.
He who grieves for what is dead or lost, he who is drowned in thinking of the past hurts himself twice. Instead of one sorrow, he gets two. Some of our regrets may be due to our failure to achieve something because we were unprepared or did not put in our best effort.
In such cases, it is better to learn the lesson and move on. American athlete Jackie Joyner-Kersee, considered to be one of the greatest female athletes ever, once said, “It is better to look ahead and prepare than to look back and regret.” Life is too short and precious to waste it in regret over the past. Thinking of past sorrows does not reduce them.
As Narada told Shuka: Dukhopghate sharire manase chapyupasthite, Yasmin na shakyate kartum yatnastannanuchintayet.
When a calamity strikes, which can cause physical or mental grief, and nothing can be done about it or what was done was not fruitful, one should cease to reflect on it with sorrow.
If our regret is because of some past mistake, we can reach out to those we erred and ask for forgiveness. If the other person is not willing to forgive or it is not possible to reach that person, we may have to forgive ourselves. If someone treated us badly, we need to forgive that person and move on. If we find ourselves wishing that some event in the past had turned out differently, we need to remind ourselves that the past is now out of our hands and there is no point obsessing over something we can't control.
A fun fact that many may not be aware of is that February 11 is celebrated as the National ‘Don’t Cry Over Spilled Milk’ Day in the US. Come next February, let the date be a reminder to keep a positive attitude.