"A recent study "tracked the symptoms of depression in people who were trying to quit (smoking) and found that they were never happier than when they were being successful, for however long that was." The process of quitting smoking actually improved the mood of all participants in the study who quit for some period of time.
Christopher Kahler, research professor at Brown University, and his colleagues studied 236 men and women seeking to quit smoking. Participants were tested for symptoms of depression one week before quitting, and at 2, 8, 16, and 28 weeks after quitting. 99 subjects never quit--they remained the unhappiest throughout the study. 77 quit temporarily--their low mood lifted while they were abstinent but descended again when they resumed smoking. 33 abstained throughout the study--these successful quitters reported the happiest feelings. (The rest of the participants didn't fall into any clear pattern.)
So, oddly, quitting smoking can be like taking an anti-depressant. Why? I'm not sure if the "quitters'" changes in mood were related to brain chemistry or to the pride of regaining control over a previously out-of-control habit. Or, maybe people become happier when they commit themselves to a particular choice, as suggested by happiness researcher Daniel Gilbert. At any rate, this study suggests that if you want to be happier, stop smoking!
Would this mood lift apply to other habits? Well, to exercise, for sure. Numerous studies show that exercise, even in small doses, boosts mood and mental health. What about weight loss? Weight loss is a trickier subject, but at least one study indicates that after a 6-month weight loss program, people suffering from depression not only lost weight but reported significant improvements in their mood".
Enough motivation to really change that bad habit (at least one of them) this year? I think so!
Read the full article at http://www.psychologytoday.com/blog/changepower/201101/could-changing-harmful-habit-make-you-happier