We all know that smoking's bad for you - but sometimes it's easier to believe the various half-truths and myths that surround smoking than to accept that it's time to give up.

Here we debunk some of those myths once and for all. Bring on the nicotine patches!

Smoking makes you sexy

In fact, male smokers are twice as likely as non-smokers to suffer impotence. Around 120,000 men in their thirties and forties are impotent in the UK as a result of smoking.

The habit will also make your skin wrinkled and can leave you looking 10 to 20 years older than you really are, according to the Government's Chief Medical Officer.

Smoking calms you down

It actually makes you more anxious - because when you aren't having a cigarette, you end up suffering nicotine withdrawal symptoms, which make you crave another. Rather than being pleasurable in itself, it's a way of easing your withdrawal - a bit like hair of the dog, really.

Your health barely suffers if you smoke fewer than 10 cigarettes a day

Sadly not true. Research shows that if you smoke one to four cigarettes a day, you're three times more likely than a non-smoker to die from lung cancer or heart disease.

What's more, there is some evidence that the number of years you smoke affects your cancer risk more than the amount you smoke each day.

Smoking 'low-tar' brands will protect my health

Low-tar cigarettes are just as harmful as regular brands, because people inhale them much more deeply to satisfy their nicotine cravings. Nor are you safe if you avoid inhaling, because you'll still be at risk of cancers of the mouth, throat and food pipe (oesophagus), which can be very disfiguring.

My gran smoked 80 a day and died in her sleep at 94, so it can't be that bad...

We all have different genes and surroundings, which make some people more vulnerable to the damage done by smoking. But smoking dramatically increases your chance of dying early and getting cancer, heart disease or another smoking-related illness.

Smoking helps you keep your weight down

This is true, in that the habit reduces your appetite and makes your body waste energy. But you can avoid weight gain if you start to take more exercise (easier when you don't smoke) and/or cut your intake of alcohol and high-calorie foods.

There's no point in stopping now - the damage is done

In fact, your body starts to recover within minutes of you quitting. Within three days, breathing will be easier and you'll have more energy; and within a few weeks, exercise will be less of a struggle.

After ten years, your risk of lung cancer is about half that of a smoker, while your risk of a heart attack is the same as non-smokers'.

The only thing that can help you give up for good is willpower

Yes, willpower is vital, but there's strong evidence that using nicotine replacement products such as gum and patches can roughly double your chances of success, because they take the edge off the cravings you will feel in your first few days.

You can get NRT on prescription from your GP and there are also prescription drugs that your GP can give you to dramatically boost your chances of success.

It's better to cut down gradually than to stop suddenly

The problem with cutting down is that you may never actually quit altogether. However, recent research shows that people who can't face going cold turkey can give up by gradually cutting back on fags while starting to use nicotine replacement therapy to fill some of their nicotine gap - then, eventually, coming off NRT.

The NHS is too poor to help me quit

In fact, the NHS runs free stop smoking groups all over the country - and you can join one by getting a referral from your GP.

For expert advice on quitting, call Quitline 0800 00 22 00, or the NHS Smoking Helpline on 0800 169 0169.

Other good sources of support and information are the British Heart Foundation and Action on Smoking and Health.