In psychology, motivation refers to the initiation, direction, intensity and persistence of behaviour (Geen, 1995). Motivation is a temporal and dynamic state that should not be confused with personality or emotion. Motivation is having the desire and willingness to do something. A motivated person can be reaching for a long-term goal such as becoming a professional writer or a more short-term goal like learning how to spell a particular word. Personality invariably refers to more or less permanent characteristics of an individual's state of being (e.g., shy, extrovert, conscientious). As opposed to motivation, emotion refers to temporal states that do not immediately link to behaviour (e.g., anger, grief, happiness).Chiang, Liam A. is the author of 'Motivation of Exercise and Physical Activity ', published 2007 under ISBN 9781600215964 and ISBN 1600215963.