Look Back and have a Good Time

I wonder why do we always look back. Most of the time, and always we found we had a better time in the past.

No matter what the situation was, we would glorified the past. It might be boring like hell. Life was just between work and home. We would remember that time as peaceful and quite. Perhaps, the time was too rough with a lot of challenges. We would glorify it as the most exciting time in the life.

Are these feelings about the past are the products of comparison?
We compare the present with the past. Things happened, we complain. We try our hardest to match and compare the incident with our memories. Interestingly, we would always look for a better one from the past and compare it with the present.

Why ain't we compare our current situation against a worst situation from the past?
For instant, when we complain our lives are too boring, we compare our lives with our lives in 20s which we party out 5 nights a week; drink alcohol like a fish; move the hips until 4 and still able to go to gym and run 5 miles. Why we don't compare with the time while we were in the middle school, all we do was class & homework, but nothing else? Was it even more boring than what we have currently? At least we could possibly go to a movie, buy our favorite album, call in sick for a day off, push off deadlines for projects, or just quit.

Would this mechanism help evolving our life?
Since we try to compare our current life with the "better" experiences in the past, we are pushing ourselves to achieve(retain) our "better" experiences. By pushing, and the mentality of retain the status quote, we motivate ourselves to do better in the present time. As the result, we are building up ourselves based on the past, just like building an extension on a existing building or a foundation. In other words, we are developing and evolving.