Why not go back to a good memory? Our brains our not as good as we think they are. Don't believe me just ask your wives

They change and morph memories good or bad depending on how we perceive them. If you go back to a good memory you may find it not as spectacular as you remember. When was the last time you had the best cigar of your life with friends only to go back later and smoke the same cigar alone to find out it isn't so great. Must be a bad cigar right? Maybe it is just our Swiss cheese brains putting a euphoric memory around the whole experience.
Personally bad or good let the past be the past and I will remember them as I remember them (right or wrong). To me the future always brings a chance for a new experience or new memory to be made.
One of my favorite quotes: "The only thing constant is change." So true every day.