Here is a verse in Proverbs (4:18) to give the elderly a hopeful outlook:
“But the path of the just is like the shining sun, that shines ever brighter unto the perfect day.” The elderly may feel their age very acutely; their strength and life may seem dimmer each day. But the truth is their path is shining brighter with the passing of each day. Sounds a bit like 2 Corinthians 4:16: “Therefore we do not lose heart. Even though our outward man is perishing, yet the inward man is being renewed day by day.”
God turns things upside down. The body starts wearing down, but the spirit of the Christian grows newer and newer, the path ahead brighter than ever. The eye of faith sees the unseen and has hope.
On the flip side: “The way of the wicked is like darkness; they do not know what makes them stumble.” (Prov. 4:19)