Better Than Our Best Days

"For this light momentary affliction is preparing for us an eternal weight of glory beyond all comparison, as we look not to the things that are seen but to the things that are unseen. For the things that are seen are transient, but the things that are unseen are eternal." (2 Corinthians 4:17-18)
Do you ever think about the best days of your life? Not as in a certain year or season in your childhood, but specific days. The best 24-hour periods of your life.
Kira and I often ask each other at the end of a year, or on an annual milestone like a birthday or anniversary, to remember the single best day of that year. It's fun to relive them. And yet it is a bittersweet thing too, because you realize that you can never relive these best days. They exist only in memories and pictures, and even those things fade with time.
I sometimes imagine that in heaven, one of the joys of living in eternity will be that we'll have the ability to re-live the best days and best memories from our earthly lives. I'll be able to return to that memory of lying in the grass and watching shooting starts at a Wisconsin summer camp as a child; or the time I spent in Oxford and Cambridge the summer after I graduated from college; or New Year's Eve, 2016, wandering around the churches of Rome and ending with a wine tasting dinner to ring in the new year in the Piazza Navona.
But I know that in heaven, all these transient things (such as 24-hour periods we once called "days") will be quaint memories compared to the "eternal weight of glory beyond all comparison" we will be experiencing. 
And in reality, the "heavenly" nature of the best days of our earthly lives is, if we're honest, more about a longing for permanence than the actual pleasures experienced in the moment. We want the days to linger. We want them to repeatable. And our awareness of their fleeting ephemerality is, strangely, part of what makes them so joyful.
Have you noticed that the most transcendent times in life often are the moments of ending, when the passing away of things is most apparent? It's the flight home after an amazing experience. It's the campfire on the last night of camp. The final song of a powerful concert. For me it's the memory of the closing worship service of Oxbridge 2005 in King's College Chapel, Cambridge. Or it's simply a sunset: the nightly, universally magnetic elegy for daylight.
Humans are instinctively moved by sunsets, intuitively aware that they are "beautiful." Why? I think it's because the sunset is the daily rehearsal of the reality that "the things that are seen are transient, but the things that are unseen are eternal" (2 Cor. 4:18). It's the visible affirmation that it is the temporality of this life that is the most beautiful, because it points beyond itself. It is not the oranges and reds and purples of a sunset that are the most beautiful; it's the fact that the colors are so dramatic, the sky so fiery and electric, for only a few moments. Then gone. 
It's a gut-level awareness we can hardly put into words, but C.S. Lewis does as good a job as anyone in his various writings about longing and joy and Sehnsucht. Take this section of The Weight of Glory:

The books or the music in which we thought the beauty was located will betray us if we trust in them; it was not in them, it only came through them, and what came through them was longing. These things—the beauty, the memory of our own past—are good images of what we really desire; but if they are mistaken for the thing itself, they turn into dumb idols, breaking the hearts of their worshippers. For they are not the thing itself; they are only the scent of a flower we have not found, the echo of a tune we have not heard, news from a country we have never yet visited.

The hope of Christianity is the hope of resurrection; it's the hope of the sunrise. It's a promise that the temporal, here-and-then-gone beauties of this life are mere teasers for the world to come.
The worst day in heaven will be better than our best days on earth. That's not an excuse to just endure this life and wait to "escape" to heaven. It's a hopeful invitation to dig in deeper into the beauty of this world: every experience, every song, every sunset.