Motivation is defined as the process that initiates, guides and maintains goal-oriented behaviors. Motivation is what causes us to act, whether it is getting a glass of water to reduce thirst or reading a book to gain knowledge.
It involves the biological, emotional, social and cognitive forces that activate behavior. In everyday usage, the term motivation is frequently used to describe why a person does something. For example, you might say that a student is so motivated to get into a clinical psychology program that she spends every night studying.
Psychologists have proposed a number of different theories of motivation, including drive theory, instinct theory and humanistic theory.