Some days ago, I was about to write a post about cynicism. It was never written due to my sleepiness. But there is another way to talk about it.
The word "forever" is an utter lie. Nothing can last forever. Neither humans, nor their creations. Not even the system. We see situations changing around us every day. The thing is, I think, to be aware of that. Sometimes, when you're in a situation, you think it's going to be for life. And then you get lazy and stop appreciating the little things that make it wonderful. (The only case that defies my concept are the eternally in love couples, but I'm mostly not refering to love here)
You probably start realizing thins when you're at the end of something, or even after the end. That nothing is for granted. That some things don't happen anymore, because we've grown past them.
You can't go to play every day and wake up in the afternoon, because you have a job. or because you're thriving to end your studies to get a job (you wish). Or because you've done it too much and from some point on, it loses it's point. And you miss the trips, the tips, the culture, the lazy days. Even though, they make you wiser.