I think of women friends in their late thirties, squaring up to face the advancing monster of the number 40. Superficially it is bloody scary. It's no longer possible to pull an all-nighter studying/working/ travelling/partying/sparkling to catch the beau, whatever, and function like a perky young thing (which is what you were then) the next day. No, a night without shut-eye leaves you shattered, incoherent and longing for a bed to sleep.

Moisturiser is no longer a frippery to be tried on like a trinket. It's a vital supply as furrows on your forehead-so maddeningly fetching as a petulant teenager, threaten to become permanent.

Trying-on sessions in clothes shops take much longer-the hips-the actual bones-have moved! Childbearing actually pried your skeleton apart but in your euphoria you didn't notice.

But the most unfair of all - in the past food was a fuel that came in the way of real life-of adventure and possibility. Now it's an obsession and you only have to look at a piece of cheesecake-not even eat the forbidden food-to put on three pounds.

When did it happen? Answer: It happened while you weren't looking.

So resentfully, you look up at your counterpart-your spouse-okay, he may be balding, may have added girth in the midsection, may be sprouting a grey hair or several on his undulating chest where fat lolls with muscle, but shockingly-and even more unfair than the cheesecake phenomena-he is actually more attractive to the opposite sex. Women simper around him, shop girls giggle, flight attendants shoot him shy smiles while he rolls back and pats his tummy.

While you the woman, advancing towards forty, anxiously think if you want another child you'd better hurry before it's too late, he swaggers languidly in his 1970 pointy high-heeled boots as if he has all the time in the world. The most unfair thing is he does. He can sire children till he's eighty if he wants.

He can believe that association with youth keeps mortality at bay, and bounce around in a disco in shiny tight pants with that 23-year-old if he wants. Hell he can marry her even if she is the same age as his children.

You ask yourself: Why?

You know the answer all along. Or you think you do. The official answer is men want youth and beauty as proof of their virility. Women want power and security (of which men generally are custodians) and don't give a hang about the pot-belly if the money keeps rolling in. So the ideal relationship is between a middle aged man and a young girl. Young men are sorted out because they are always in demand.

That leaves the late thirty-somethings watching with horror as the big "four-O" comes hurtling at them.

The question then is: Is there life after 40 for women?

Is it a pit of despair, atrophy, sagging body parts and waiting at the window, curtains slightly parted for the children to come home while the husband makes a clown of himself in a leather jacket and a gold chain?

Or is there more?

I was shocked to find out from older women that not only is there life after forty, it gets better, it's the most brilliant thing to happen to you. And this is not some Mickey Mouse self-help hype either.

The women who say this in so many different ways are, variously, painters, ladies of the manor, recently divorced women, happily married women, women having roaring affairs with younger men, and incredibly successful women. They are also simple housewives, homemakers and self-employed women.

I hear their voices now in snatches, and cut and paste them together in the following paragraphs.

Firstly, after 40 attracting and keeping men is no longer as important as it was in your thirties when you needed them either to sire or support children. And you honestly don't care too much if they run off because you've created a whole life around you. Your children grow up and your unexpected treat is they become YOUR best friends and support.

Secondly, all that juggling you do in your twenties and thirties pays off.

All those moments you stole away from cooking or writing that report to support a friend through heartache, the times you sneaked away for a few hours to bond with the girls, the times you spent on the phone laughing and crying with people other than the main man in your life pays off. You realise that suddenly you have two decades of friendship and dozens of friends in your life. You have witnesses to your life.

Thirdly, you come into your own. You've dealt with all those agonising insecurities of your teens and twenties, you've survived motherhood and the rat race of your work place, and you've managed to juggle motherhood, marriage, a career. You've got in some traveling and some wild times. You've created a home, cooked some family lunches and seen that spark of childhood, of warmth, depth and recognition reflected in the eyes of your parents and siblings.

Finally, as you close your eyes at night, even in the darkest, coldest moments, you are able to visualise yourself sitting on the beach at sunset, the sun's glow a symbol of the centre of your world, tremulous at times, but always alight. On the sand are the footsteps of all the people you have loved and will love, the faces of people you've woken up with, those whose arms you've cried into, those you've linked arms and jumped up with.

After forty there's the fullness of life.

So that's what growing older means. With the spark and energy of a 16-year-old and the wisdom of a nearly 40-year-old, without knowing it you create poetry out of your life, like so many women before and after you.