'We cannot motivate others' – from this view of motivation, we can see that the decision to act relates to our own internal needs, perceptions and drives. We can only motivate ourself. Others can provide suggestions, directives or advice. However the choice of what and how – or even when and why we behave is internal. "Motivation is the fire within". Others, like incentives, are external. While they may serve as "fuel for the fire", we still control whether we allow it to "fire us up".
Are all people motivated similarly? The answer clearly is 'No'. People are diverse. Diverse in age, gender, personality and in ethnicity. In addition, their socio-economic status differs. What motivates a young, male, single, new employee, who lives at home with his parents, will be different from a mid-career married with female, with a home mortgage and children.
We each have the social needs for achievement, affiliation or power but they differ in their intensity for each personality type.