Many people are unhappy because there was some point in their past where there was some glory day, and as they get older they're not creating more glory days. They reflect on a time that they will never reach again, and it brings some level of dissatisfaction into their lives. I have circumvented that by simply making incumbent upon myself to always be productive in ways that are consistent with my physical body, my mental state of knowledge, but more important, my presumed growth in wisdom that would come with age.