Cantankerous. That is what we are all set to become. It is the inevitable consequence of the new focus on choice in the NHS. Those who shout the loudest get first choice and the rest can go hang.

It is an excellent prescription for a long life. Last weekend, I attended my father-in-law's 94th birthday and, without delving into family grief, it is fair to say that in a long and productive life he has not been backward in expressing his needs.

He is ministered to by my mother-in-law, aged 89, who still produces roast dinners with all the trimmings for her family. Never less than a dozen different items on the plate - it is a matter of motherly pride.

They are an impressive couple and you do not need to spend long in their company to learn how they have survived. As my brother-in-law proposed a toast to absent friends at the gathering last weekend, his mother fired back, a steely glint in her one good eye: "Why should we? They could have been here." Tolerance and resignation are not virtues in their household.

All the evidence shows that wilful people, who insist on staying in control of their own lives, live longer than the more compliant "sweet old folk'' who make the good patients favoured by doctors and nurses.

People in control of their lives stay healthy and live longer than those who allow themselves to be buffeted by events. Determined old bats are also less prone to medical ageism, blatant examples of which are to be found in the NHS. Old people are routinely offered poorer treatment than the young, but the worse outcome is blamed on their age.

The first imperative for those wishing to be a healthy hundred, therefore, is to be informed, stay in command and be thoroughly obstreperous in refusing to be fobbed off with second-rate medical care.

But this command, which has always been true, will become doubly so in the new consumer-led NHS. And not just for the old, but for all of us.

I am not convinced that the politicians who advocate choice - from all parts of the political spectrum - have thought this through. Coping with a nation of Victor Meldrews will be a tall order for the NHS.

Imagine your local GP's surgery crammed with people demanding to be sent to the best place for hips or hearts or hernias, only to find that several hundred have got there first and the waiting list stretches from here to next Christmas.

Imagine outpatients filled with people demanding to see surgeon x or doctor y, only to be told that their favourite medic has been seconded to the fast-track centre down the road and is now performing cataract ops three at a time.

Don't get me wrong - I am in favour of more choice in the NHS. Those who argue that most patients are uninterested in choice, such as doctors at the recent British Medical Association conference in Llandudno, and that all they want is a good local hospital where they can rely on prompt, high-quality service are missing the point - or at least half of it.

It may well be true that what people want when they fall ill is a high-quality, local service they can rely on. But if control of the NHS is to be transferred from Whitehall to the front line, as the Government has rightly undertaken to do, then some mechanism has to be substituted for the loss of central control, to ensure that quality and performance are maintained. That mechanism is choice. It is the only lever we will have in the devolved NHS to ensure hospital trusts and GPs raise their game.

No, my problem is not with the principle, it is with the practice. Believing in choice is one thing, exercising it is another. When I encounter the NHS as a patient I find I am overcome by passivity and a sense of fatalism. I place myself in the care of the system, await my turn and trust it to look after my welfare and to do its best. I am so imbued with the communitarian values of the NHS that the idea of exercising choice seems alien.

And here is the problem. Every choice we make is at someone else's expense. If I choose the top cancer hospital to deal with my tumour, I take the place of someone who might benefit equally - or more - from the same top-flight treatment. This does not sit easily with the NHS's principle of providing care to all on the basis of need. Choice favours those who bang the table hardest, while the meek go the wall.

So here is my health tip for the week: hone that cantankerous streak, and polish up your bloody-minded side. You know you can be obstreperous - now just do it.