Years ago I saw a painting of an old moneylender in the Prado in Madrid. The painter, José de Ribera, depicted her character in a way no photographer could. The habits of a lifetime of greed and cheating people out of their last penny were deeply etched in her face.

Lately I’ve been noticing how my long-time friends and colleagues have changed over time. (I, of course, still look the same while everyone else visibly ages.) In particular, habits of action and attitude grow ever stronger with age, just as Ribera’s painting makes so plain. Older is not necessarily wiser. It may just be more firmly set in one’s ways.
Some habits age better than others. A friend, now in her 80s, has been impulsive and bold in word and deed in all the decades I’ve known her. But what was daring for a middle-aged woman has become foolhardy. She simply refuses to recognize that her aging body is no longer able to do what it once did. And what had been determination has transformed into willfulness.
Anger or bitterness?
Another habit that doesn’t age well is anger. Anger can be good, especially if it leads to positive action. But if we let it fester, anger becomes bitterness. Paul’s command, “Do not let the sun go down on your anger,” (Ephesians 4:26) sets a limit on how long we harbor it so it doesn’t become corrosive.
I’ve known people who nurse their resentments—whether initially justified or not—for many years. Instead of honestly confronting someone who has wronged them—and maybe making the relationship better—they let resentment grow until they lash out uncontrollably. By then the original provocation is long past, most likely forgotten by everyone else.
Assuming the worst about someone’s motives can spark anger and fuel resentment. Hanlon’s razor is a good test here: “Never attribute to malice what can adequately be explained by stupidity.” Of course, stupidity can do plenty of harm on its own. But assuming the worst about people’s motives—which are usually beyond our ability to perceive—just adds to an already hostile atmosphere.
Habits that age well
[I]t is character that tells. … I mean such qualities or acquirements as intelligence, thoughtfulness, conscientiousness, right-mindedness, patience, fortitude, long-suffering and unconquerable resolve.
…We know not of the future, and cannot plan for it much. But we can hold our spirits and our bodies so pure and high, we may cherish such thoughts and such ideals, and dream such dreams of lofty purpose, that we can determine and know what manner of men we will be whenever and wherever the hour strikes, that calls to noble action. This predestination God has given us in charge. No man becomes suddenly different from his habit and cherished thought. We carry our accustomed manners with us. And it was the boyhood you brought from your homes which made you men; which braced your hearts, which shone upon your foreheads, which held you steadfast in mind and body, and lifted these heights of Gettysburg of immortal glory.
—Joshua Lawrence Chamberlain, dedication of the 20th Maine monument at Gettysburg, 3 October 1889