A doctor once told my Nan that it would be more beneficial to smoke up to 5 a day rather than give up, he told her that it would help her cough up any crap she needed to get rid or easier than not smoking at all! Quite frankly if you've smoked for ages then your better off just cutting down. Every time my Dad tries to give up he comes down with something really nasty, so I would suggest to just cut down as much as is possible without causing yourself any stress