Within self-determination theory, a distinction is made between intrinsic and extrinsic motivation (Deci & Ryan 2000). Intrinsic motivation is understood as motivation that originates within the individual; it is interwoven with the self. Instead of intrinsic motivation, the term self-motivation is sometimes used. If a person is intrinsically motivated, the initiative and regulation of their behavior lie within themselves. They do something because they want to, because it is satisfying, or because they recognize that a particular activity is in the interest of their self-development.

Intrinsic motivation is also understood as the inherent tendency to seek novelty and challenges, to develop and exercise one's own capabilities, to explore, and to learn. Intrinsic motivation is often seen as essential for people's cognitive and social development and is a significant source of enjoyment and vitality throughout life. Intrinsic motivation always involves some form of voluntariness and personal support for activities. This involves an internal locus of causality (deCharms, 1968). This means that with this type of motivation, people perceive that the cause of their behavior lies within themselves, or is not determined or imposed from outside.

Besides intrinsic motivation, there is also extrinsic motivation. This type of motivation arises from external pressure or a mandate. This can include social pressure to engage in certain activities that a person doesn't support themselves, or that don't align with their personal goals and identity. With extrinsic motivation, an activity is performed to achieve a specific outcome, often to obtain a reward or avoid punishment.

Conforming to formal rules and laws can be considered extrinsic motivation. But extrinsic motivation can also occur in a more subtle way, for example, to avoid feelings of guilt or shame. In short, extrinsic motivation involves an external locus of causality. The person then has the impression that the cause of their behavior is not internal, but is imposed from outside (Deci & Ryan, 2000).

Self-determination theory demonstrates that when behavior is based on strong intrinsic motivation, it will lead to increased effort, persistence, interest, and excitement in performing activities. Imposed goals and external pressure can undermine intrinsic motivation for activities. This shifts a person's motivation to an external locus of causality. A person then feels less motivated for a particular activity. Instead, they now feel controlled by external factors, leading to a loss of appreciation and interest in the activity itself. Therefore, for optimal motivation for activities, a certain self-determination of behavior is crucial.