For more than three decades, best selling American writer Judith Viorst has been marking the milestones of her life in verse. The titles capture the mood of the changing years "It's Hard to be Hip Over Thirty," "How Did I Get to be Forty," "Forever Fifty," and now a new book called "Suddenly Sixty And Other Shocks of Later Life."

Judith Viorst says she thought "Forever Fifty" might be her last book of poems about life's passages. She's known for writing humorous verses, and she wasn't sure she'd find anything funny about being in her sixties. But she's still laughing, and that's just one of the surprises she explores in "Suddenly Sixty."

Judith Viorst: "The big surprise is that it's not as traumatic as I expected it to be. I don't think I understood even as recently as 20 years ago that the sixties were still full of life and energy."

Nancy Beardsley: "And do you think it means something different to be in your sixties today than it did in decades earlier?"

Judith Viorst: "Oh you bet. Absolutely. The idea of a 60-something woman as being sexless, useless because she's past her childbearing prime - I think those were ideas at one point. And the women in their 60s I know today are very vital, energetic, involved people. Every single woman I know is moving out of her own private life into community activities. A lot of women I know at this age are learning new stuff. I've got a friend who's discovered a talent for painting and drawing that's taking everyone's breath away. So that sense of adventure is a very new idea."

The sixties can also be a time for new relationships, and old ones that change or deepen in unexpected ways. Judith Viorst reads a poem called "The Blissful Couple:"

They laugh together.
Read together.
Dance together.
Paint together.
Listen to music together.
Walk, holding hands together.

They love exchanging warm, wet, mushy kisses.
He rushes to greet her,
His arms outstretched,
Joyfully calling her name,
When he sees her arrive.

Who, you are wondering is this blissful couple?
She is his grandma.
He is almost five.

Judith Viorst says she's found a big difference between being a mother and a grandmother. She said, "When you have children, they become, as somebody else once said, the parents' report card - proof of what a good person you are, what an intelligent person you are, and all the rest. With grandchildren, you can take one step back and enjoy them, and it is a wonderful luxury."

And while you no longer get to tell your grown children what to do, says Judith Viorst, you can watch with pride as they become caring parents themselves. There are other changes: A long lasting marriage can be appreciated for what she calls the "quiet joys," like sharing a morning newspaper together. Old friendships become more precious as the years of common history accumulate. But growing older brings new challenges as well.

"There are a collection of ailments I had never even heard of, couldn't even pronounce some of them, that are very much part of this decade," she said. "This is a stage where you recognize your President, your accountant, your doctor - everybody is much younger than you are, and that you can't call yourself middle aged because that's what your children almost are. And even though this is basically a funny book, I think you have to acknowledge the sobering parts of being in your sixties before you start laughing."

And that's why "Suddenly Sixty" sometimes sounds wistful, as in these lines from a poem called "If Only."

If only having insomnia gave me courage.
If only eating chocolate made me smart.
If only French fried potatoes helped me remember.
If only they sometimes also helped me forget.

If only one morning I'd leap out of bed feeling ready and willing and eager to welcome old age.
But not yet.
Not yet.
Not yet.
Please not yet.

Although not everything she writes about actually happened to her, Judith Viorst does borrow heavily from her own life to write her books. She's also the author of a non-fiction work called "Necessary Losses," about the transitions involved in aging. And she's written more than a dozen children's stories, including a contemporary classic called "Alexander and the Terrible, Horrible No Good Very Bad Day." While all her books reflect her interest in marriage and family, she believes "Suddenly Sixty" adds another theme. She said, "I think the 60s is very much a decade of gratitude when you do count your blessings, when you stop when something is moving and you notice it right here and now - those beautiful, sunlit moments of life."

Will she still be feeling funny enough to write a book of poems about her 70s? Judith Viorst says she's not committing herself yet. But she does have several other projects in the works, including another children's story and a book for adults on marriage. "Suddenly Sixty" was published by Simon and Schuster, 1230 Avenue of the Americas, New York, New York 10020.