Living in the past is a trap of the physical leading to Karma. It leads to comparison, dissatisfaction, negative reflection and inability to be in the present. The objective of being in the present and not the past is to take that which was experienced in the past and use it to affect correct responses to challenges that are presented to us in the “now”.
Saying that one could have done better when reflecting on actions made in the past, based upon “current” knowledge, or thinking/stating that “things” were better in the past, only creates dissatisfaction with one’s past performance, creating a continuous regime of negative reflection.
We react and act based upon our experience and ability to deal with that presented to us, the “quality of event” being how we deal with that presented to us with the tools of ability and prior experience. Accepting that how we reacted and acted was the best that we could have achieved, given the circumstances, is called “living in the now”. Recognizing this negates the need to constantly refer to the past in comparison to the “near present” or “now”, allowing us to move forward in our evolutionary growth rather than turning that achieved into a function of Karma, based upon physical performance.
This does not negate the need to learn from our mistakes, but rather negate the need to chastise ourselves when we spot the mistakes in “correct action” retrospectively.