Answer:
Soldiers fight it but never changes.
What is always coming but never arrives?
Lovely and round, I shine with pale light, Grown in the darkness, a lady’s delight.
You could do this to a motion, see it on a watch, or place this in a race.
Retired people want these to be large and birds want them to hatch.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.