Motivation is the driving force that impels individuals to action and is important for managers to promote productivity in employees. There are two types of needs that motivate individuals: innate needs which are physiological requirements for survival like food and water, and acquired needs which are learned from one's culture or environment. A model of motivation shows that unfulfilled needs, wants, or desires create tension that drives behavior aimed at a goal, with the goal's fulfillment then reducing the tension.