Three Key Motivations

Every good character needs motivation...

Motivation towards a goal, or towards an ideal way of life. Motivation is a large part of job performance, but they're also very obscure to the person that is supposedly motivated. That is to say, that people very rarely know what really motivates them. This is because motivations are largely unconscious. There are three such motivations, mainly:

Achievement: Which is the individuals drive to achieve, excel and improve in any manner of things. (Or all things).

Power: Which is the individuals drive to influence, manage and lead people. Whether that be as a hero, a sergeant, a teacher, or something more obscure.

Affiliation: Which is the individuals drive to form meaningful or warm relationships with other people. Not limited to merely partnership.

It's important to discern what is the driving force behind a character because if you learn what drives the character, it's very easy to work out what the character will do in any given situation. If they forsake for example, the opportunity to succeed at something, when they are driven by achievement, then you'd know to have them be bothered by this decision. If they were ordered around constantly, or subject to the arrogance of someone they believe unfounded, whilst motivated with power, you'd potentially have them act angered or bothered by this.

Supporting Research
The Achievement Motive (1953)
The Achieving Society (1961)
Testing for Competence (1973)
Human Motivation (1987)