Edward Fischer tells the story of an American woman touring Mexico who came upon a boy selling oranges at midmorning in a village marketplace. After selecting an orange for herself, she offered to help the boy by buying the six oranges he had left, but he would only sell three.

"Why don't you sell me the other three?" she asked."What will I do in the afternoon?" he replied.

And that is the secret of growing older, says Fischer: as with this boy - knowing what to do with yourself in the afternoon - the afternoon of life.

Fischer, the author of "Life in the Afternoon: Good Ways of Growing Older" (Paulist Press), has recommendations in his book about how to fill such afternoons, which, incidentally, he wrote in his 71st year:

As you age, your attitude counts, he says. "Maturing is not an achievement for early years alone, but for all of life. . .. No matter how old you get you should still have something to offer the universe."

All seniors, in fact, share a common vocation: "All need to give courage to those who are still on the way." Growing older with grace allows the senior to be a model to those "who will someday face the inconveniences of accumulated years."

With discipline, one grows old with dignity, he emphasizes. Such discipline involves making dozens of right decisions daily: "The decision to sit up instead of slump, the decision not to have just one more drink, the decision to stop eating before feeling stuffed, the decision to bestir the body instead of lolling about all day. And decisions of the spirit - the desire to keep interested, to shun self pity, to avoid bitterness."

"You are an artist whose work is to create yourself right up to the end," observes Fischer. So your senior years give you your last chance to become who you really are and to uncover your latent possibilities.

To turn your life into a work of art, you must have purpose for existing, so find that purpose, he urges: Take risks and follow your intuition to find a destiny or a "calling." And don't worry about whether that calling is humble: "I knew a waiter, a laundress, a policeman, a bus driver and a blacksmith who turned humble jobs into destinies. By the way they approached their work they made me realize that the thing done with love is greater than the work itself," he stresses.

In growing older, see yourself as the creator of your present, rather than the product of your past, advises Fischer. That means keeping your nose pressed firmly against the "Now." making the moment "work," being aware of sounds, smells and tastes, and giving attention to the instant.

Fretting over the past is foolish, he emphasizes. As a character says in George Eliot's Adam Bede: "It's but little good you do a-watering the last year's crop."

Fretting about the future is similar folly: "The cemetery is filled with people who are worried about catastrophe overtaking them only to have death arrive first."

Just as the development of the self is a lifelong work, then so is the process of learning, observes Fischer, who notes that history provides heroric examples of old people maintaining productivity while contemporaries slipped into senility. The productive ones "handled their lives as a continuous unit of mental and emotional development, by never retiring, by never ceasing to learn."

Strive continually, then, for the "fresh experience" and take on the attitude of one 99-year-old - still active on skis and in a canoe - who relates: "I've always wanted to know what is on the other side of the hill."

Fischer, who each year "logs more miles on foot than in an automobile," encourages walking every day. "What a walk does for the spirit is more important than what it does for the cardiovascular system," he says. "Something about walking stimulates thought, soothes the soul and smoothes out a rumpled psyche. While putting one foot in front of another the cosmos does not seem so near collapse as when sitting before a TV set watching the evening news. The end is not yet."

If growing older gives more time for walking, it also gives more time for reading, says Fischer, who takes his daily walk to the library, where he plays the "serendipity game:" "That means moving slowly along the shelves of books, always hoping for a happy discovery."

Fischer urges recording your life in journals and memoirs, which has infinite value to posterity. "My grandfather's walking stick I value," he says, "but I would cherish even more a few hundred pages of his life's story."

Writing also aids you in gaining perspective: "Rereading a journal is like coming upon a wall where in youth you stood from time to time to chalk your height. Or it is like finding an old family album. How you changed, and you hadn't noticed!" It also gives you a glimpse of what you are becoming.

Preparation for growing old should start early in life, Fischer notes. This column but samples the rich advice given in his book for reading - and growing - whether it be the afternoon, or morning, of life.