It would be great if we could remember the good memories only, which is possible if... indeed there's an if.... if we force ourselves to only remember the good things since the memory is based on the last memory we had of the last memory it's memory and not the event itself. Who knows if we actively think this way (and are taught to do so) we will not only live a nightmare if alzheimer's disease shows up and we go back to the days of our childhood.