Motivation is a need or desire that energizes and directs behavior. It is the internal or external force that initiates, sustains, and guides action toward a goal.

Biological motives such as hunger, thirst, and sex arise from physiological imbalances and homeostatic mechanisms. Psychological motives include the need for achievement, affiliation, and autonomy. Theories range from drive-reduction accounts that emphasize the reduction of internal tension to incentive theories that emphasize the pull of external rewards, and to cognitive theories that stress expectations, goals, and self-efficacy.

Intrinsic motivation arises from the inherent interest or satisfaction of an activity; extrinsic motivation arises from separable outcomes such as pay or praise. The quality and persistence of behavior often differ under the two forms. Cultural values, individual differences, and situational factors all shape what people find motivating and how strongly they pursue it.

Behavior that continues in the face of obstacles usually has a motivational source behind it.