I would imagine 'nostalgia' make us feel good. Not without reason are psychologists trying to analyze the enduring appeal of the past which, till recently, was considered a 'sickness'. Derived from the Greek 'nostos' (return) and 'algos' (pain), nostalgia no longer means 'return of the pain'. On the contrary, it now improves mood, increases self-esteem, strengthens social bonds and imbues life with meaning. Else, why would a forty-plus be ecstatic about a long forgotten cold drink?
Sheer experience tells us that middle-aged might score better over younger generation in being nostalgic. May be for the modern geeks there are gadgets and girlfriends to keep themselves glued to the 'present'. But for the middle aged, being nostalgic reminds them that their lives have been worthwhile, that they are happy and that life has some sense of purpose or meaning.
Given the monotony of the present-day life, nostalgia is seemingly becoming a great escape to the good olden days. But there are those, and a good number of them, for whom the past is a flashback of painful memories. For such souls, 'nostalgia workouts' are the next big thing that the neighborhood gyms will soon come up with. But for the blissful those who have had their first brush with love, being nostalgic is for a sure a way of life that is not only personal but private too that the 'market' has yet to tap into!