I'm reading Learn to Grow Old by Paul Tournier, who also wrote The Meaning of Persons, A Doctor's Casebook in the Light of the Bible, and others. So far I find it quite good. In one chapter he quotes about Hubert Beuve-Mery, then recently retired editor of Le Monde that "Everyone stresses the independence of mind with which he runs his paper, 'without ever being afraid to take a line that runs contrary to the views not only of the powers that be--which is nothing--but also contrary to those of its readership.'"
This shows courage in a land with variety of points of view among the newspapers, but is wearyingly patronizing in a land with a monoculture in the newsroom. We have two daily newspapers in town: a somewhat leftist journal and a socialist one. The University student dailies are likewise a Democratic paper and a Marxist/"transnational progressivist" rag. Nothing conservative, or even Republican.
At any rate, Tournier says that old age displays what we always were. When at work we may have many co-workers and acquaintances who give us the illusion of having friends. But retire, and you don't have anything to talk about with them anymore. If your hobbies were just amusements, they will bore you when you have nothing else to do. If you use grumbling and grousing to motivate yourself (be honest), you will have nothing left but the grumbling when your powers decline. If you are interested in people as persons and in things because of people, you will likewise retain these interests and habits into old age.
As you might expect, retirement day is too late to try to cultivate a new character; or better say that it is now very hard to change.