To give someone the incentive to act in a certain way is to motivate that person. If you give your dad a food-processor for his birthday, you might motivate him to help out with the cooking.
The verb motivate means to prompt or incite. By giving speeches on college campuses across the country, John F. Kennedy motivated a lot of young people to join the Peace Corps in the early 1960s. People are not always motivated in positive ways, however. When a crime is described as racially motivated, it means the perpetrators picked their victim because of the color of his skin.