Economist Tim Harford has an excellent riposte to the argument of a socialized health service that you have to watch your habits:

Those who argue that smoking should be restricted because of the costs to the National Health Service are on even thinner ice. If I offered to pay for your private medical insurance out of the goodness of my heart, you would be unimpressed, and rightly so, if I then turned round and claimed that your smoking was now costing me money and so I had the right to hide your cigarettes. Similarly, the UK’s decision to fund healthcare from tax revenues does not thereby give the government the right to restrict our freedom to take personal risks. In any case, this is a dangerous argument. We all have to die in the end, and a sudden smoking-related heart attack is a cheap way to go compared with 30 years of state pension or round-the-clock nursing care for someone with Alzheimer’s disease. If smoking turned out to be a money-saver for the government, would that really justify a cigarette subsidy? Economic arguments can be double-edged; sometimes they are best not wielded.

The entire piece, on the economic absurdity of the British smoking ban, is worth reading.