Using tobacco or any other drug for that matter offers some kind of reward, it may not be the healthiest option but we are inclined to do it.
Think of your brain as the muscle that it is, it gets exercised and formed into the brain it is now. The beauty of our brain is it has the ability to mold and transform just like the muscles in the rest of your body, this is called neuroplasticity. In addition, the brain is reinforced by chemicals that are released (dopamine) when you interact with your environment or others make you feel good.
Take smoking or chewing for example; since the age you started using tobacco you have been pairing this substance with whatever the thing or situation may be. This in turn gets worked into that muscle memory of your brain and becomes hard wired to the point where maybe you do not even think about it, it’s more of an automatic thing that occurs. Therefore, you are getting what we like to call a double sided reward. You are allowing the routine (avoiding discomfort of a new routine) and you are getting nicotine, which releases dopamine (a natural feel good chemical). This becomes the norm or habit if you will.
Now, go back to when you were a kid and remember your parents telling you “don’t worry, practice makes perfect.” They were right! It takes time to rewire the brain circuits to choose the healthier learned behavior over the tobacco, whether it is nicotine replacements or a new found coping skill e.g. deep breathing, sucking on candy, going on a walk, etc. Keep the positive thoughts flowing and reinforcing the replacement behavior, it is hard, and you may slip up, which is okay!