On my morning dog walk, litter-picking as I go, I listen to the radio on my digital Walkman. The contrast between the calm pleasures of the walk and what I hear on the earphones is every day more of a chasm.

Must Heathrow compete with Dubai as a world-class airport? After yesterday morning's argy-bargy on the Today programme over Terminal 5 and a third runway, it was a wonderful relief to hear the 86-year-old actress Liz Smith on Desert Island Discs. Left motherless at 2 and abandoned by her adored father; left by her husband to struggle with two young children; failing to make it as an actress until she was 50, she still found something to appreciate in every stage of her life. “If I wasn't a little bit batty, life would be more difficult,” she said. (When she first arrived in London in the 1940s, she went to a house she saw advertised, and on the doorstep paid the £1,700 asking price, without even looking inside.)

I happened to visit Liz Smith recently, in her tiny retirement flat. It overlooks a Tube station platform, so there is always a view from the window of the rat race going about its ratty, bustling business. She exuded contentment and curiosity, she laughed at everything: the perfect example of an old lady who knows how to enjoy life.

The reason this particularly struck me was that, the night before, I had been in the audience at the London School of Economics, at a seminar where Sylvia Ann Hewlett, who runs the Centre for Work-Life Policy in Manhattan, spoke on her research into the growth of our long-hours culture and its effects on individual lives. Dr Hewlett's subject is Extreme Jobs - the fast-paced, high-earning careers offered by City corporations, banks, and law and accountancy firms. When she began this research, she had held another seminar where I recall meeting a chic-suited young Chinese woman working for an international bank, who smilingly introduced herself with an instant word-picture of her fast-track life. “I have a husband, two children, a dog, a cat - and I spend more time in the air than I do on the ground.” Frightful!

Dr Hewlett identifies six main “stressors” that cause exhaustion and burnout among those committed to a working week of 60-plus hours. These include rigidity combined with unpredictability; fast pace and tight deadlines; availability to clients 24/7; constant travel; and work-related events outside regular work hours.

And one of the chief stressors is the number of frustrating interruptions to the working day because of “our canny communication devices”. With several screens on your desk, an average of three minutes' attention is given to any single task without interruption. In our hair-trigger response to the ping of the e-mail we are like trained rats, in a corporate culture that expects an immediate response, Dr Hewlett says - “as if we were emergency surgeons making life-or-death decisions”. This scrambling and jarring of attention, especially in a day of ten or eleven hours, kills any hope of serenity. “And at the end of that day, there's usually a commute back to a domestic life of multitasking home and children.”

Unsurprisingly, many women - and men - cannot take much more than seven years of this work-overload. (This is known as Flight Risk: highly trained executives leaving their jobs.) Eighty per cent of women in such jobs confided to Dr Hewlett's focus groups that they cannot see themselves keeping it up for another year.

“Every time I commute to the office, leaving my two-year-old with the nanny, I wonder if it's worth it” is a typical view. A significant portion (20 per cent) of women who escape from extreme jobs choose to start their own businesses, which may involve even longer hours. But with a crucial difference: “OK, I still work crazy hours - but I am in control.”

Of course, high-octane jobs produce different results for men and women. The more a man earns, the more power he has, and the more likely he is to have a wife, or a series of wives, and children. The high-earning woman has power in the workplace, but is much less likely to have a marriage or children.

This reminded me of a conversation I had recently in Dublin with Mary-Louise Kenny, who runs a dating agency in the centre of the Celtic Tiger's most successful city. She spoke of the high number of Irish women now forging ahead in accountancy, banking and business: “They have the black suits. They have shedloads of money. They own several properties. They travel. But then they get to 40 and realise they haven't got the man.”

Dr Hewlett is herself a fizzing dynamo, raised in the Welsh valleys, with five children aged from 10 to 30. The happy news from her think-tank is that corporations are listening to her wisdom. Lehman Brothers and BP are two of the corporations trying to rein in their employees' hectic work commitment in an effort to reduce the flight risk of executives jumping out “like frogs from a wheelbarrow”.

Listening to Thursday night's discussion gave me a wonderful feeling of tranquillity. Gratitude that I am not in an extreme job. Contentment with my low-intensity life, with a zero desire for air travel, nightclubs, bling or any of the other peculiar spending excesses of those who get and spend much more than I.

After meeting Dr Peter Carey, a gentle Buddhist history professor at Oxford recently, I have been thinking of the value of slow time, and meditation, and viewing life in a different way. As Anna Ford - who has jettisoned her sharp white news-reading jackets with a sense of relief - told me the other day, there is no greater balm for the soul than strolling around famous gardens on winter mornings. And since my husband is currently recuperating from a hip operation, I have been sampling the pleasures of slowing down the pace.

By a bizarre coincidence, leaping on my e-mails like a trained rat before writing this, I found among the 30 screaming junk mails urging me to borrow money, spend more, upgrade my mobile, elongate my non-existent penis and accumulate more stuff, I found a soothing message: “Remember the five simple rules to be happy. Free your heart from hatred. Free your mind from worries. Live simply. Give more. Expect less.” How wise.

Valerie Grove's latest book is A Voyage Round John Mortimer: The Authorised Biography

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