Habits are routines of behavior that are repeated regularly and tend to occur subconsciously, without directly thinking consciously about them. Habitual behavior sometimes goes unnoticed in persons exhibiting them, because it is often unnecessary to engage in self-analysis when undertaking in routine tasks. Habituation is an extremely simple form of learning, in which an organism, after a period of exposure to a stimulus, stops responding to that stimulus in varied manners. Habits are sometimes compulsory.
Habit formation is the process by which a behaviour becomes habitual. As behaviours are repeated in a consistent context, there is an incremental increase in the link between the context and the action. This increases the automaticity of the behaviour in that context. Features of an automatic behaviour are all or some of: efficiency, lack of awareness, unintentionality, uncontrollability. Habit formation is modelled as an increase in automaticity with number of repetitions up to an asymptote.
Author John Tesh advises that it takes about 21 days to establish or break a habit.
Habits and goals
The habit–goal interface is constrained by the particular manner in which habits are learned and represented in memory. Specifically, the associative learning underlying habits is characterized by the slow, incremental accrual of information over time in procedural memory Habits can either benefit or hurt the goals a person set for themselves.
Goals guide habits most fundamentally by providing the initial outcome-oriented impetus for response repetition. In this sense, habits often are a vestige of past goal pursuit.
A bad habit is a negative behaviour pattern. Common examples include: procrastination, fidgeting, overspending, nail-biting.
Will and intention
A key factor in distinguishing a bad habit from an addiction or mental disease is the element of willpower. If a person still seems to have control over the behaviour then it is just a habit. Good intentions are able to override the negative effect of bad habits but their effect seems to be independent and additive — the bad habits remain but are subdued rather than cancelled.
Eliminating bad habits
According to author Bill Borcherdt, the best time to correct a bad habit is immediately, before it becomes established. So, bad habits are best prevented from developing in childhood.
There are many techniques for removing bad habits once they have become established. One example is withdrawal of reinforcers - identifying and removing the factors which trigger the habit and encourage its persistence. The basal ganglia appears to remember the context that triggers a habit, meaning they can be revived if triggers reappear. 
All modern social institutions arise from the evolution of the primitive customs of your savage ancestors; the conventions of today are the modified and expanded customs of yesterday. What habit is to the individual, custom is to the group; and group customs develop into folkways or tribal traditions--mass conventions. From these early beginnings all of the institutions of present-day human society take their humble origin. (68:4.1)
Step forth with renewed vigor in executing your life plan. Walk not in a habitual state of action. Throw off the chains of programmed interaction, and open yourselves to seeing your siblings as children of God. For while they are not perfect, they carry within them the most perfect presence: a fragment of God. Will
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- John Tesh (2008), Intelligence for Your Life, p. 39
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