The Time of Old Age by Henry Morris, Ph.D.
 

"Now also when I am old and greyheaded, O God, forsake me not; until I have shewed thy strength unto this generation, and thy power to every one that is to come." (Psalm 71:18)

One tends to grow resentful against the limitations and increasing infirmities associated with aging, even complaining to God and others about growing old--at least until one considers the alternative! We need to remember that, as long as the Lord preserves our lives, He has some ministry for us to perform for "this generation" and "to every one that is to come."

The Scriptures abound with promises of blessing in old age, so growing old should be an occasion for rejoicing and deepened commitment to whatever the Lord enables one to do. "The righteous shall flourish like the palm tree: . . . Those that be planted in the house of the LORD shall flourish in the courts of our God. They shall still bring forth fruit in old age" (Psalm 92:12-14). But if there develops a tendency to grow spiritually cold with age, the admonition of Paul is appropriate. "Aged men |should| be sober, grave, temperate, sound in faith, in charity, in patience. The aged women likewise, that they be in behaviour as becometh holiness, . . . teachers of good things" (Titus 2:2-3).

Thus the heartfelt prayer of the psalmist in our text is still appropriate today, for all who will, sooner than they think, enter the time of old age. Note also the following prayer: "Cast me not off in the time of old age; forsake me not when my strength faileth" (Psalm 71:9). That God will answer such a prayer, offered in faith and sincerity, was affirmed by David when he said: "I have been young, and now am old; yet have I not seen the righteous forsaken, nor his seed begging bread" (Psalm 37:25). The time of old age can be a time of happy harvest, if we have sowed the seeds of good fruit. HMM

http://www.icr.org/article/6469/