The treadmill is good. On cold, rainy days, the treadmill provides a warm, dry workout. I use the treadmill often in the dark winter months when I rely heavily on artificial light. However, the treadmill is also a boring road to nowhere. It is a paltry falsification of the real thing: a run outside.
Running outside is better. I can think of few things that are more relaxing than a warm, breezy outdoor run at the park. Sunshine pours through the trees, and I absorb the beautiful golden rays. The jog takes me somewhere, and there is freedom.
Life is good. At least, life on earth has many good things: family, friends, sunshine, running, cookies, photography, etc. But while there are many good things on earth, life on earth is like running on a treadmill. This temporary life is a mediocre substitution for life in heaven.
Eternal life is better.
No eye has seen, no ear has heard, no heart has imagined, what God has prepared for those who love Him.
– I Corinthians 2:9
The joys of heaven cannot be compared to the minimal goodness of earth. Heaven is lit by the glory of God (Revelation 21:23) and is filled with everlasting worship (Revelation 4). The bejeweled city is free from the curse of sin (Revelation 21-22). We will have new bodies that never face hunger or death (Revelation 7:16). Most importantly, we will have pure fellowship with the Father (Revelation 22:3).
All winter long, I run on the treadmill, preparing for the day that will be warm enough, bright enough, and dry enough for an outdoor run.
Likewise, we must redeem our time on earth and prepare for eternity in the presence of God.
Be very careful, then, how you live—not as unwise but as wise, making the most of every opportunity, because the days are evil.
– Ephesians 5:15-16