A survey of smokers found 24% class themselves as social smokers but more than one in three of these buy up to a packet a day.
Around 60% had tried giving up, with one in six of those who had tried to stop succeeding for more than a year before going back to their old habits.
Some 13% took up smoking again because friends smoked and they did not like being left alone on nights out. Other reasons included the effects of alcohol and a football team losing.
Of those who did go back to smoking, 47% had initially cut down.
The poll also found that 54% admitted to smoking in banned areas. One in six said this was because it was too wet and cold to smoke outside, while 14% said the area was not policed well.
Catherine Cox, primary care manager at The Co-operative Pharmacy, which conducted the poll, said: "Just smoking a few cigarettes a day has an impact on your health."