The primary sources of motivation proposed by psychologists are instincts, drives, and needs and arousal levels. These are the intrinsic mental forces that cause a person to act.
Instincts are patterns of inborn behavior. Many psychologists suggest that we are motivated to act by these fixed and basic human patterns. On the other hand, we are also subject to biological drives that prompt action. For instance, our biological need for food will prompt us to eat. Drive theory highlights our biological need to fulfill these drives. The arousal theory is based on the idea that people will be motivated to act in a way that produces within them an optimal level of arousal. Whereas people with high arousal needs can be motivated to engage in highly stimulating behaviors, those with low arousal needs are often drawn to more subdued activities.
Motivation can come from an intrinsic or extrinsic source. Intrinsic motivation is prompted solely by a desire to attain personal gratification through a sense of accomplishment. Extrinsic motivation involves outside influences and is closely associated with the desire to gain an award or recognition. Since motives are not able to be seen, we infer that they exist because we observe certain behaviors.