Motivation is the reason for which humans and other animals initiate, continue, or terminate a behavior at a given time. Motivational states are commonly understood as forces acting within the agent that create a disposition to engage in goal-directed behavior. It is often held that different mental states compete with each other and that only the strongest state determines behavior. This means that we can be motivated to do something without actually doing it. The paradigmatic mental state providing motivation is desire. But various other states, such as beliefs about what one ought to do or intentions, may also provide motivation. Motivation is derived from the word 'motive', which denotes a person's needs, desires, wants, or urges. It is the process of motivating individuals to take action in order to achieve a goal. The psychological elements fueling people's behavior in the context of job goals might include a desire for money.

Various competing theories have been proposed concerning the content of motivational states. They are known as content theories and aim to describe what goals usually or always motivate people. Abraham Maslow's hierarchy of needs and the ERG theory, for example, posit that humans have certain needs, which are responsible for motivation. Some of these needs, like for food and water, are more basic than other needs, such as for respect from others. On this view, the higher needs can only provide motivation once the lower needs have been fulfilled. Behaviorist theories try to explain behavior solely in terms of the relation between the situation and external, observable behavior without explicit reference to conscious mental states.

Motivation may be either intrinsic, if the activity is desired because it is inherently interesting or enjoyable, or extrinsic, if the agent's goal is an external reward distinct from the activity itself. It has been argued that intrinsic motivation has more beneficial outcomes than extrinsic motivation. Motivational states can also be categorized according to whether the agent is fully aware of why he acts the way he does or not, referred to as conscious and unconscious motivation. Motivation is closely related to practical rationality. A central idea in this field is that we should be motivated to perform an action if we believe that we should perform it. Failing to fulfill this requirement results in cases of irrationality, known as akrasia or weakness of the will, in which there is a discrepancy between our beliefs about what we should do and our actions.

Research on motivation has been employed in various fields. In the field of business, a central question concerns work motivation, for example, what measures an employer can use to ensure that his employees are motivated. Motivation is also of particular interest to educational psychologists because of its crucial role in student learning. Specific interest has been given to the effects of intrinsic and extrinsic motivation in this field.