I don’t believe it is productive to dwell on what you could do over, however it is productive to know how to do things differently the next time a similar situation arises. So if you didn’t spend enough time with a parent in the past do so in the present, if that is not possible, do so with an in-law parent or an elderly aunt or uncle. Teach someone else that too late is just too late.
This doesn’t just apply to parents. If you distanced yourself from your children for whatever reason, even if you were right and they were wrong, don’t stand on ceremony and kovod, remember life’s too short and find a different way to bring about a different outcome. Value the opportunity to put it in the past and build a better future. Find new ways to handle old situations to make life better and happier. After all would you rather be right or would you rather be happy? Many times you just can’t have both.
We all have our fair share of regrets, but rather than dwell on regrets turn them into opportunities to do better.