Motivational forces drive our behaviors, thoughts, and feelings. Psychologists have proposed different theories addressing the needs that create these drives within us. Let’s look at the three most prominent theories of motivation. Some theories, like drive-reduction theory, best explain motivation related to physiological needs. Other theories focus on psychological needs, such as the need for an optimum level of stimulation, as described in arousal theory. In his hierarchy of needs, Abraham Maslow combined various drives and proposed that we are motivated to meet some needs before others.