Chew carrots: A healthy snack can help you overcome your nicotine cravings (and the urge to bring something to your mouth). Carrots, celery, radishes, bell peppers in slices and other fresh vegetables are good too.
Exercise / shower: this produces endorphins / soothes and relieves stress and anxiety.
Nicotine is rapidly depleted from the body during times of severe stress. Or, in general, it happens that sometimes we want something so harmful.
You'd better eat something from fast food. And if you had stress the day before, calm down and do pleasant things.
Nicotine is not only poisonous, but very quickly addictive. In the process of smoking, a person receives a dose of nicotine, and thus relieves nicotine withdrawal. The withdrawal itself feels like a slight feeling of hunger - a weak aching emptiness inside. However, in addition to physical dependence, there is a factor of psychological dependence: the belief that cigarettes in one way or another affect your condition, mood, and so on.
If you have never smoked (sat down or quit) in your life, then, most likely, your desire to smoke is associated with personal delusions about smoking. Just remember that smoking relieves nicotine withdrawal, but does not affect anything else: it does not help either with stress or with concentration.