You can eat five portions of fruit and veg a day and exercise regularly, but healthy behaviour means little if you continue to smoke.
The message that 'smoking is bad for you' is an old one, so not everyone gives it their full attention. Below we list the health risks of smoking.
Most people know that smoking can cause lung cancer, but it can also cause many other cancers and illnesses.
Smoking kills around 114,000 people in the UK each year.
Of these deaths, about 42,800 are from smoking-related cancers, 30,600 from cardiovascular disease and 29,100 die slowly from emphysema and other chronic lung diseases.
Cigarettes contain more than 4000 chemical compounds and at least 400 toxic substances.
When you inhale, a cigarette burns at 700°C at the tip and around 60°C in the core. This heat breaks down the tobacco to produce various toxins.
As a cigarette burns, the residues are concentrated towards the butt.
The products that are most damaging are:
tar, a carcinogen (substance that causes cancer)
nicotine is addictive and increases cholesterol levels in your body
carbon monoxide reduces oxygen in the body
components of the gas and particulate phases cause chronic obstructive pulmonary disorder (COPD).
The damage caused by smoking is influenced by:
the number of cigarettes smoked
whether the cigarette has a filter
how the tobacco has been prepared.
Smoking raises blood pressure, which can cause hypertension (high blood pressure) - a risk factor for heart attacks and stroke.
Couples who smoke are more likely to have fertility problems than couples who are non-smokers.
Smoking worsens asthma and counteracts asthma medication by worsening the inflammation of the airways that the medicine tries to ease.
The blood vessels in the eye are sensitive and can be easily damaged by smoke, causing a bloodshot appearance and itchiness.
Heavy smokers are twice as likely to get macular degeneration, resulting in the gradual loss of eyesight.
*Smokers run an increased risk of cataracts.
*Smokers take 25 per cent more sick days year than non-smokers.
*Smoking stains your teeth and gums.
*Smoking increases your risk of periodontal disease, which causes swollen gums, bad breath and teeth to fall out.
*Smoking causes an acid taste in the mouth and contributes to the development of ulcers.
*Smoking also affects your looks: smokers have paler skin and more wrinkles. This is because smoking reduces the blood supply to the skin and lowers levels of vitamin A.