From biting nails, to caffeine, all the way to drinking. Every habit can be broken down to this system above famously coined by Charles Duhigg in his book The Power of Habit. It is called The Habit Loop and it consists of three parts being cue, routine, and reward. This cycles in repetition so efficiently that you do not question why you do some of the things you do. If you give it some thought, it is rare that you find yourself thinking about how you brush your teeth or the order in which you dress yourself. You have already mapped the neural network and stored it away so you never have to bring it up again because you bury it in validation. This is the dangerous and awesome power of habits because has the power to benefit or deteriorate you.
Cue
The cue is the trigger for the action that you do. It usually has something to do with your location, social reasons, emotional states, or timing. For example, the cue for smoking could be anxiety or restlessness building up. It could also be that they smoke everyday at exactly the same time making their schedule prompts the internal desire. The cue sparks the automatic processing that you store away so you rarely question the impulse. If smoking is difficult to grasp as a want, most can relate to the inclination to drinking coffee at certain parts of the day due to low energy.
Routine
The routine is the easiest element to understand. You want to cease the act of consuming caffeine or eating unhealthy. The routine is the act that follows the cue in a response to satisfy the desire.
Reward
The reward is the reasoning behind deciding why the steps prior are worth doing again in the future. It provides a positive support for the routine, increasing the odds of doing it again. The reward can be something tangible like money (gambling), or intangible like social validation. I like the energy coffee offers so I will drink it more often. The downside is I will be tired if I do not drink it throughout my day.
Using the Habit Loop to your Benefit
The maker of the Habit Loop has a system to play with habits in your life. First step is to identify the routine. This should be somewhat easy to point to as if there is a desire to change it, you should know what is being changed. Next step is to experiment with the rewards. For example, if you drink coffee habitually, you might be just looking for an energy. There are different ways to achieve this that is not coffee. Trying different things to achieve the same result is an effective way to realign a habit. Another way to change the usual is to isolate the cue. This can be more difficult living in such a stimulus driven world but asking what you were feeling right before enacting the habit is an easy method to help with the process. Final step is to note the cue and change the reward.
If you have the urge to smoke, try doing something that will give you the same stimulus. Perhaps it is painting or reading a book. Whatever it may be, make it an experience you want to partake in. Try something new so you can trade out smoking with a cool hobby you picked up.