“Good habits are hard to form and easy to live with. Bad habits are easy to form and hard to live with. Pay attention. Be aware . If we don’t consciously form good ones, we will unconsciously form bad ones.”
― Mark Matteson
Without guidance we tend to learn on our own through a mistake-laden process. Unfortunately, this path leads a person to establish bad habits that become not only hard to live with but also very hard to get rid of. Take smoking or any other self-defeating habit for example. Those habits end up controlling the person. Even after the self-made victim decides to kick the bad habit, they end up working hard to stop the bad habit.
A habit is made up of three parts: queue or trigger, routine, and reward. In order to change a bad habit one must replace the routine. Nature abhors a vacuum therefore under normal circumstances one cannot just quit a bad habit.
For more info on habits check out the following books.