"No," replies the doctor. "It will just seem longer."
One of the down sides of trying to live to a ripe old age has always been the self-denial involved in reaching the goal, particularly when there is no guarantee it will work anyway.
Apocryphal tales abound of how men and women who have relentlessly pounded the pavements for years and lived on lentils and uncooked organic cabbage leaves, have been rewarded with a premature death.
But, despite the sceptics, increasing numbers of men and particularly women are reaching 100 and beyond, ages that were science fiction at the turn of the century when the average Victorian died at 47 compared to today's 75. These centenarians are often seen as a beacon of hope by the rest of us who want to believe that their prolonged existence means that everyone can live longer, and we scan their lives looking for clues to the secrets of longevity.
Finally, the first book on how to make it to 100 has arrived, and it rounds up those clues and gives practical hints on increasing the chances of getting a birthday telegram from Buckingham Palace.
While most of the vast range of DIY-health books on the market have relatively modest aims, ranging from 101 cures for indigestion to coping with male menopause, the authors of The Longevity Strategy - How to Live to 100 have gone for the big one. "When you finish reading this book you will have everything you need to know to increase your chances of becoming a vigorous centenarian, living to be 100 and liking it," enthuse the authors, Dr Richard Restak and David Mahoney.
Reaching the goal of 100, they say, relies on a combination of strategies, starting, of course, with the hope that you have inherited a full deck of the right genes with no mutations or missing bits. But genes, stress the authors, are only part of the strategy: "We have to overcome the tendency to put too much emphasis on our genetic inheritance. We have to stop blaming our genes for our health and longevity. While it is true that genetics play a part in our susceptibility to certain diseases, heredity accounts for only about one quarter of the variation in human life spans," they say.
Which means that genes contribute no more than 25 per cent to our health, with the environment and behaviour providing the rest. Or, put another way, whereas genes govern how long we might live, lifestyle and environment determine how close we will get to that maximum.
Although individual centenarians are very different, researchers have, not surprisingly, found some common traits including a basic optimism, a willingness to adapt, a sense of personal power, resilience, and self- esteem. To help everyone to aspire to reaching 100, the authors lay down 31 separate tactics whereby state of mind is at least as important as physical health. What's important, it seems, is taking control, having a positive attitude to life, having good self-esteem, acquiring stress- coping skills and health-promoting habits, and taking frequent holidays.
Aside from emphasising the, by now familiar though often ignored, health- education messages about eating habits, smoking and alcohol, much of the book offers advice on a range of areas, from the advantages of laughing and computer literacy to the disadvantages of retirement and having no friends.
And those embarking on the path to longevity are warned that some common personality traits, like hostility, depression, anxiety, stress and social isolation, are to be avoided or got rid of at all costs.
"People who have few social contacts and who report little pleasure in the company of others die prematurely. Survival after heart attack or cancer is lessened in people with few friends. Even keeping a pet reduces the likelihood of death and disability. Talking to a dog or cat lowers the owner's blood pressure and slows the pulse," say the authors.
Depression needs to be rooted out, too, because it lowers the immune system defences, and sufferers are up to three times more likely to have a heart attack. Stress must also be eliminated because of links with heart attacks, ulcers, migraine headaches and irritable bowel symptoms.
Humour and laughter, however, are vital assets because they lead to a drop in the stress hormone, epinephrine, say the authors, while also boosting the immune system by increasing the body's defences against viruses and other infections. A hearty laugh speeds up the heart rate, improves circulation and works enough muscles to qualify as an aerobic exercise.
The success of humour is nowhere more obvious, it seems, than at Mumbai in India where there are 37 laughing clubs. "The members breathe deeply, reach for the sky to reduce their inhibitions, and force a 'ho, ho, ha, ha' until all the members are laughing uproariously. According to the club's founder, Dr Madan Kataria, laughter is contagious, healthful and reduces stress," assert the authors.
Firm advice is offered too about retiring - don't. Change careers, do something different, but never, ever retire, is the advice, because mental activity is vital to keep the brain alive and alert.
"Slowing down, relaxing, spending time engaged exclusively in recreational activities - if this is your idea of retirement, you'd better change it. Eject the word retirement from your vocabulary."
Computers can also play a crucial part in the quest for longevity, because, as the book points out, there is nothing more depressing and disempowering than to feel that the world is passing you by.
"If you are currently middle-aged and parked beside the information highway instead of being on it, turn on to the ramp. You can enter cyberspace no matter how old you are. Older people with online opportunities experience enhanced social well-being and reduced loneliness and depression."
As the Millennium approaches, the indications are that the average lifespan will continue to rise with Britain predicted to have 30,000 centenarians in 20 years time.
And as more people survive to such ages, demand will increase for longevity to be pushed back even further; perhaps, suggest the authors, beyond the current record of 122. But even that may not be enough to satisfy those who, on the whole, would like to live for ever.
As Woody Allen famously said, "I don't want to achieve immortality through my work, I want to achieve it through not dying."
'The Longevity Strategy: How to Live to 100 Using the Brain-Body Connection' by Richard Restak and David Mahoney; 2 April, Wiley, pounds 17.99Reuse content