Overview
A bad habit is a behaviour pattern perceived as negative. Common examples include: procrastination, overspending and
nail-biting.
Development
Research on habit formation generally suggests an individual can acquire a new habit on average over 66 days. This process is marked by an asymptomatic increase of the behavior, with the initial acceleration slowing to a plateau after the said time period. There are several variations regarding the period of development. The time to break a bad habit or change an unhealthy behavioral pattern such as smoking may take longer.
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 behavior 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 canceled.
Prevention
The best time to correct a bad habit is immediately, before it becomes established. So, bad habits are best prevented from developing in childhood.
From Wikipedia (CC BY-SA 4.0).