Increased irritability is one of the strangely accepted facts about quitting smoking. As nicotine is slowly removed from the bloodstream, you become irritable and unable to concentrate. Why?
The accepted scientific cause for irritability is that that it's a part of nicotine withdrawal, and has to be treated with just like the rest of the symptoms of withdrawal. This is not exactly the case, however.
Virtually everyone who quits smoking begins to regret their decision a few days in, as their learned connection between daily activities and smoking cause them to have cravings for cigarettes. You become frustrated weighing the benefits of quitting versus the immediate gain of being able to concentrate instead of constantly thinking about smoking.
It's all understandable, I went through the same thing the first few times I tried quitting smoking, unsuccessfully, I might add. Occasionally, you give in to the cravings and go right back to smoking. Alternately, you could stick to your guns and push through … and keep having the cravings for months. That does not sound very fun at all.
The trick to quitting smoking and not having to look back is to convince your mind, from the beginning, that it does not need cigarettes in order to function. Remember, non-smokers do not feel the urge to light up when they're stressed, why should you?
You feel the urge to smoke when, for example, you're stressed because you've trained your mind to believe that smoking somehow eases your stress. Sure, it may take your mind off the fact that you're stressed, but it does not really solve anything.