This is the most basic theory of motivation. According to this, animals (including humans) are genetically predisposed towards certain actions. According to William James, human instincts, like anger, love, shame and fear are responsible for motivating them to perform certain actions.
While this theory lost traction due to lack of depth in terms of explaining motivations and actions, it still holds true as far as the role of genetics in motivation is concerned.
The drive theory is a little similar to the instinct theory, and according to this, humans are motivated by their needs to perform actions. The theory focuses on internal tension as a result of unfulfilled needs. For instance, this theory explains the act of drinking water by focusing on the state of thirst motivating a person to fulfill the need for water.
This theory however, does not explain all actions and the motivations behind them. For instance, you can, and often do, drink and eat without any internal tension related to thirst or hunger.
The incentive theory leaves towards behavioral studies, linking human actions to rewards. If we look at the act of eating food, according to the incentive theory, the pleasure and satisfaction we derive from tasty and wholesome food is our motivation behind eating.
The arousal theory stipulates that humans are constantly struggling towards maintaining an optimal level of arousal. For instance, if your arousal level is slow, you seek fun and entertainment and if your arousal level is high, you tend to want to relax and get some alone time. According to this theory, your actions are always aimed at achieving a balance.
The humanistic theory is not as simple as the others and focuses on human cognition as the force behind actions. Abraham Maslow’s pyramid, showing the hierarchy of needs, shows this very well. According to him, people are motivated by different forces at different levels and stages. As a human progresses up the ladder, his/her motivating forces change.