12 reasons why people are obsessed with nostalgia
After the age of 30, when we think back on these times, the painful events become dimmer and dimmer. We shape and re-shape our life stories, reworking the narrative in a way that enhances the way we feel about ourselves now (Whitbourne, 1985). It's adaptive to recall the happy, not the sad, events from our past. However, it's also important to reword some of those sad events. If we only focus on the positive, we'll lose touch with the reality of the events that actually shaped who we are now.