"Only '90s kids will understand." "Do you remember when Disney Channel was good?" "Do you remember when..." These are all phrases that our Millennial generation is constantly discussing. All of the old television shows and movies have become a staple in our generation. Shows and movies such as "Sky High," "Courage the Cowardly Dog" and "The Suite Life of Zach and Cody" are all shows we often reminisce about, and gain the feeling of nostalgia just by talking about them. But a question dawned on me the other day, "Why are we constantly thinking of the past instead of living in the moment?"

According to Alan R. Hirsch in his report, “Nostalgia: A Neuropsychiatric Understanding,” nostalgia is a yearning for an idealized past — “a longing for a sanitized impression of the past, what in psychoanalysis is referred to as a screen memory — not a true recreation of the past, but rather a combination of many different memories, all integrated together, and in the process all negative emotions filtered out.”

However, it seems nostalgia isn't relating to a certain memory, but rather an emotional state.

For example, in 1908, Freud recognized a strong link between odors and the emotions.

Later, scientific findings backed up this observation, proving that odor is the strongest sense connected to emotion due to the nose's direct connection with the olfactory lobe in the limbic system — the area of the brain considered the seat of the emotions.

Thus, while the average person can smell 10,000 odors, no two people smell the same thing. We react to smells differently, associate them with different things and yearn for them differently.

This usually is an occurrence with millennials aged 16–28. We put a specific emotion with a specified time era/period, and we constantly remember that emotion felt during those times.

However, it makes sense that those in the most turbulent and unsettled time of their lives would yearn for the simplicity and safety of childhood. In your 20s and 30s, you are lost in the upheaval of everything you once knew to complete isolation and independence.

It counteracts depression.

For many years, those experiencing extreme nostalgia were diagnosed as depressed. Indulging in memories of the past was seen as a sign of homesickness and refusal to enjoy the present. It was seen as lack of commitment to the future and a burdening attachment to the past.

According to John Tierney of The New York Times, living in the past — or nostalgia — was deemed a disorder since the 17th century, when a Swiss physician attributed soldiers' mental and physical ailments to their longing to return home.

However, since more research has been conducted, it's been proven that nostalgia actually works to counteract depression.

The act of reminiscing has been shown to counteract loneliness and anxiety, while also promoting personal interactions and improving the longevity of marriages. When people speak fondly and lovingly of the past, they also tend to become more hopeful for the future. By recalling the past, they look forward to what's to come.

It gives us a reason to live.

More powerful than the future, the past gives us reason to carry on. Rather than facing the unknown, we go back to the past to remember why life is worth living. We latch on to memories of happiness to give us faith in the future.

Clay Routledge of North Dakota State University states, “Nostalgia serves a crucial existential function. It brings to mind cherished experiences that assure us we are valued people who have meaningful lives.”

He goes on to explain that those who participate in nostalgia are most likely better off when coping with realities of death. When thinking back to your life and the moments that comprised it, you find value and meaning in it. You are no longer burdened with the heavy weight that your life went unfulfilled.