However, it is not as a psalm of Solomon that this poem has commended itself so deeply to the synagogue and church. It is because it portrays the ideal king, and in the minds of Christian people this ideal king has always rightly been understood to be the Lord Jesus Christ. 

Looking first back and then ahead, brings us to the present, the third way in which David deals with the limitations of old age. He looks to the past to remind himself of God's faithfulness and power. He looks to the future to remind himself of the work yet to be done. Then, having done both of those things, he turns to the present and begins to do exactly what he has been talking about. He bears witness to God now. What he praises God for chiefly is his righteousness (vv. 19-21) and faithfulness (vv. 22-24).

I suppose there are some people who in their old age only look back to the past and are often quite unhappy as they do. They think of what they have had and lost or what they wish they could have had and never did. The present does not mean much to them except as a basis for complaining about their multiplying aches and pains, and they are afraid to look forward. They are afraid of dying. David's approach to old age was not like this.

This leads us to the second important element of this psalm. For the reflections David gives us concerning old age are not so we will wring our hands and complain about how bad it is to grow old, but the contrary. David wants us to see that even old age is given to us by God, and therefore is one of his good gifts that should be used for his glory and the blessing and well-being of others.

It is not fun to be old, especially in America. At other times and in other cultures old age had advantages to offset its disadvantages. Elderly persons were honored and respected. Their wisdom was valued. That is no longer true in America or in the West generally. Here we value youth, and the culture is so oriented to youthful interests that many old people even try to dress and act like teenagers. David didn't have those problems, of course. But the problems he had as a result of his old age were serious and even universal. In fact, they are the most basic problems of all.