The cleverest thing I ever did was to be born in the 1946-1965 baby-boom generation. Through sheer force of numbers we have flexed our collective muscle since the cradle. We invented the teens, forced political change through civil rights street protests, put feminism on the political agenda, controlled our reproduction and insisted on careers for women. Now I and my generation are on the brink of redefining growing old. The silver revolution is already under way in America, and when America sneezes, we get flu. It can't happen too soon.

In America there are 76 million baby-boomers. They are into internet dating, Viagra and cosmetic surgery (it has tripled for the over-60s). Businesses to cater for the silver market are mushrooming and advertising is playing catch-up. As those in employment reach retirement age, they are leaving a huge shortfall in the full-time workforce. Therefore, they have the clout to negotiate a three-day week or a nine-month year, which allows them to spend the winter in the sun. There is a boom in second homes.

By comparison, UK baby-boomers seem to be unaware of their potential power. Yet here the over-65s will overtake the under-16s in just eight years. By 2025, one-third of the UK population will be over 55 and there will be more over-60s than under-25s for the first time. It could be a demographic nightmare, with an ever-smaller workforce bearing the cost of maintaining a growing dependent geriatric population. It won't be: the doom-mongers are wrong.

What the statistics don't take into account is the revolution in attitude which the baby-boomers are about to demonstrate. If the newly-retired and soon-to-be-retired hold true to their history, the notion of old age is on the brink of reinvention. The baby-boomers have challenged orthodoxy at every stage in their lives. Do you think they'll stop in older age? I don't.

In 2004, UK baby-boomers owned 80% of the country's wealth. We had 80% of top-of-the-range cars, took 80% of cruises and bought 50% of skincare products. This is not a group that will embrace dependency. As we hit our fifties and sixties, it would be foolish to expect a sharp rise in the sale of beige anoraks and flat shoes. Not for us the bungalow, the day trip, free grandchild-minding and school dinners reinvented as meals on wheels.

Unlike our forebears, who were worn out by manual labour, we are the healthiest generation ever. We are living longer and staying fitter. A man who turned 60 in 1981 could expect to live for 16 years and a woman of the same age for 21 years. Today, a man of 60 has a 20-year life expectancy (though, scandalously, not in some of the poorest parts of Scotland) and a woman 23. Most of us not only want to stay economically active, we are mentally and physically capable of doing so since most of us will suffer severe age-related illnesses only in the last year or so of our lives.

Pessimists have been wringing their hands at the projected demographic trend. They warn of pensioner poverty, of 70% of pensioners living on means-tested benefit. The number-crunchers aren't factoring in what demanding and inventive consumers they're reducing to statistics. The figures may look gloomy. The people they represent are not. They are still at the forefront of our political, cultural, industrial and academic life. What's more, they have every desire to stay there.

If they haven't taken a grip yet on the next phase of their lives, it will be because they haven't woken up to the realisation that the "they" who are the retired are rapidly becoming the "us" who have no intention of going out to grass. Britain's baby-boomers have the same appetite for life as their American counterparts; we just have not, yet, coalesced again into a group force. It's time that we did.

One of the most powerful lobbying organisations in the US is the American Association of Retired People. It has 35 million members. Here the charity Age Concern (the very name makes victims of its members) has set up the much more upbeat "Heyday" to fill the same role.

According to Heyday, two-thirds of the retired over-50s in the UK find it impossible to get new jobs because employers are wedded to the notion of youth culture.

This is the baby-boomers' new battle and we'll win it when the shortage of supply of younger workers makes itself felt and when those approaching retirement re-discover their group power. The generation that fought for the expansion of individual freedom, that embraced irreverence and trounced deference will gather its forces once more in this most important battle of all.

It is time to squash the myth that only youth and beauty have value. We need to remember that character, wisdom and experience do, too. It is time to reassert ourselves, American-style. If we don't, what awaits when our savings have run out is a pension that is not even tied to earnings growth. (That is how today's elderly are treated, despite the fact that they contribute £10bn in kind to the economy as unpaid carers.) Our generation, which has called the shots until now, will not submit to it.

Once the boomers rediscover their fighting spirit, the rest will fall into place. Political parties will waken up to us again. Just look at Labour this week. It is pushing David Miliband who, despite his lack of appetite for the fray, is being sold as a challenger to Brown on the basis that at 41 he represents the younger generation. Has no-one noticed that the largest chunk of the electorate is Brown's generation? Hillary Clinton is running for the White House and no-one is telling her she's too old. Nancy Pelosi is the first woman speaker of Congress at 66.

Television hasn't cottoned on either. We baby-boomers are the television generation yet few of our icons remain on the screen. One or two men with white hair still front current affairs programmes but the over-50s are rarities. When advertisers here get the message, we will once more see our own age group in the commercial breaks and then increasingly on the programmes in between. We like icons who look like us, who have the same reference points as we do. Most of all, we like the notion that those who don't appreciate that what we like matters will shortly get their comeuppance.