Organisers of Wednesday's No Smoking Day predict this year's event will help 85,000 smokers give up their habit.
Smoking is linked to many diseases
It is expected that one in three UK smokers - about 4m people - will take steps towards giving up, with the 85,000 quitting for good.
The initiative, begun in 1984, has helped 1.2m smokers quit, figures show - saving the NHS £1.5bn over 22 years.
Think tank the Future Foundation predicts just 8% will smoke by 2050. Smoking kills 115,000 in the UK a year.
Ben Youdan, chief executive of No Smoking Day, the charity which co-ordinates the campaign, said the introduction of NHS stop smoking services had helped many people to quit.
What happens when you give up
After 20 mins: Blood pressure and pulse rate return to normal
Eight hours: Poisonous nicotine and carbon monoxide levels reduce by half, and oxygen levels return to normal
24 hours: Carbon monoxide totally eliminated from the body
48 hours: No nicotine left in body - senses of taste and smell greatly improved
72 hours: Breathing has become easier as bronchial tubes start to relax
2-12 weeks: Circulation improving
3-9 months: Lung capacity improves by up to 10%
One year: Risk of heart attack halved
Ten years: Lung cancer risk halved
15 Years: Same chance of a heart attack as lifetime non-smoker
Source: British Heart Foundation
The availability of nicotine replacement therapy (NRT) on prescription had also improved success rates over the years.
But he said: "We know that stopping together with others gives smokers an extra boost, and our figures show that you're twice as likely to succeed if you give up today, No Smoking Day."
Mr Youdan also called on the government to introduce a total ban on smoking in all public places.
"We've come a long way in the last 22 years with advertising bans, pack warnings, and NHS help for smokers who want to stop, but there is still a long way to go."
The Future Foundation report, for Nicorette, predicts that smoking will decline due to developments such as more effective stop smoking aids, increased legislation to reform smoking behaviour and lawsuits against tobacco companies forcing them out of business.
Simon Clark, director of the smokers' lobby group Forest, said: "The original aim of No Smoking Day, which was to encourage people to give up, has now been replaced by an element of coercion.
"It is now all about trying to force people to give up by encouraging organisations to implement smoking bans. That is against the original spirit of the day."
Figures from the British Heart Foundation show smoking just three to six cigarettes a day doubles the chances of having a heart attack.
One in five people in Britain die from smoking, more than 115,000 every year.
Doctors say that quitting smoking is the single most important thing anyone can do to protect themselves against heart disease.
Professor David Phillips, of the Institute of Cancer Research, said: "Tobacco is deadly and is linked with many different types of cancer as well as many other conditions which affect the senses and day-to-day quality of life."