We are held back, limited, and restricted in our present-day experiences so long as we hold on to the past. Our past is not in control of our present. Some people seem to enjoy holding on to negative feelings as indicated by their conversation habits regarding disappointments, frustrations, resentments, and problems.
Dwelling on the past makes you ineffective today. You are a different person now, and so are the other people that your feelings center around. Emotional reactions of the past should not be carried over into our present-day experience. Why be dominated by the ignorance of your earlier, more immature days?
Today is the only day you can live, so give your full attention to living well now. Remember that today is the first day of the rest of your life.