Sounds strange, but many of us try and do this again and again. We endlessly obsess, re-live, revisit or replay scenes from our past in the hope we will gain a better understanding or clarity about our present lives. Some things are best forgotten and to waste more of your valuable energy revisiting them makes no sense.
For instance someone may have upset you that you do not particularly care for, so why then do you give away more of your valuable energy discussing it with anyone within earshot? We all fall into this trap sometimes, but the key is to become more aware of when you are doing this and stop yourself. Change the topic, no matter how difficult it is. This may seem hard to do in the beginning, particularly if you are having a juicy venting session with a friend, but think about it, does the person you are discussing deserve more of your precious time? Move on and let it go.
We also fall prey to trying to change our past. For instance you may feel that your parents did not do their best for you whilst you were growing up. Acknowledging and exploring this may be important, but be wary of letting it dominant your present life. As Dr Robert Holden puts it
"To be really happy, you have to give up all hopes of having a perfect past."
What a powerful quote, none of us have had a perfect past, but that does not have to dictate our present or future life.
Focus on all the things that are great in your present life and whilst you're at it show yourself some serious care and acknowledge how well you have coped with things in your past that were difficult.