The public is being urged to take more responsibility for its health to cut smoking and drinking and take more exercise.
But in this week's Scrubbing Up, Professor Richard Ashcroft, a bio-ethics expert at Queen Mary, University of London, warns that will-power is often too weak.
Health Secretary Andrew Lansley told the doctors' union, the British Medical Association, it was time for people to take more responsibility for the health of themselves and their families.
Lansley argued that if we want to see people eating healthier diets, smoking less, and taking more exercise, then an approach based on lecturing people, supervising what they eat, and banning things would fail - unless people's behaviours changed too.
He was not saying - as conservatives (small c) often do - that it is none of the state's business what people eat.
Quite the opposite: he was explicitly arguing for the state having a role in changing how people behave.
What Mr Lansley was doing was arguing that we need to look at the ways we try to encourage healthy eating, giving up smoking, etc.
Do they work? Or do they sometimes achieve the opposite of what we intended?
But politicians who advocate patients taking greater control of their own healthcare fail to understand what really motivates people.
It's all very noble, but recent behavioural science research challenges the idea that people are rational decision-makers where their personal health is concerned. People are not always in full control of their behaviour.
A prime example is smokers. Despite knowing the damage their vice causes, the instant fix they get from a cigarette overrides any consideration for long-term wellbeing.
The problem is not really that we all have things we like, and knowingly eat or drink, which aren't all that good for us.
A little of what you fancy
Most of us know that a little of what you fancy does you good, and most of the time we're right.
Sometimes we'll knowingly "trade off" different goals we have: I want that ice cream, and I want lose weight, and right now I choose the icecream, knowing that the plan to lose weight is taking a hit. But that's a conscious choice, even if I regret it later.
The problem is that often we make these sorts of choices unconsciously, or make mistakes. Or our commitment to our goals is weaker than we think. Or - hardest of all - our will is weak.
In other words, it isn't just that I trade off icecream against weight loss in favour of icecream now. It's that I do so systematically.
My behaviour is shaped by forces I don't know about, don't understand, and even when I do, I find hard to resist or control.
A lot of this is about getting better informed, but health education is only part of the story.
Some health information campaigns are very compelling - think of the anti-smoking campaigns which use children talking about their parents' lung cancers. But the evidence that they work is weak.
And they rarely have the seductive appeal of the campaigns of the tobacco and alcohol industries. Health campaigns are rarely about pleasure and enjoyment, and they are rarely cool.
But even when I get 'clean' information that isn't intended to bias my choices one way or another - my habits and thought processes are just as important, if not more important, than what I know.
Lecturing people fails both because no one likes to be hectored, and because people don't necessarily learn from it. And they have other sources of information as well.
Usually what drives me is circumstance, habit and short term reward. So the trick is to find ways to rewire my habits, change my circumstances, and make the rewards pull me in ways I want to go, and not in ways that are harmful to me. And that's hard.
It is also hard to see how getting industries which have an interest in getting me to buy their (harmful) products in increasing quantities can be trusted with promoting health education and health behaviour change at the same time.
With government advertising budgets being slashed and the Change4Life scheme being handed over to the private sector, this is a serious concern to many working for public health.
The sting in the tail of Mr Lansley's tale is that "personal responsibility" might be what's at the root of the problem, not the solution.