A Definition of An Intrinsic Motivation

 I t is a kind of motivation that originates from the inside of a person rather than from the external side or the reward system like giving something to let them motivated.
                                  The motivation comes from the pleasure one gets from the task itself or from the sense of satisfaction in completing or even working on a task.

An intrinsically motivated person will work on a math equation, for example, because it is enjoyable. Or an intrinsically motivated person will work on a solution to a problem because the challenge of finding a solution is provides a sense of pleasure. In neither case does the person work on the task because there is some reward involved, such as a prize, a payment, or in the case of students, a grade.