A promise is a statement in which one undertakes to do something or to fulfill an obligation. It is often associated with a specific time, occasion or person. The promise can be formal or informal, and it can be made to oneself or to someone else.
The promise can be expressed as a goal to be achieved, an ideal to be realized, and can therefore generate an expectation, a hope or an aspiration in the one who receives it. This expectation is a source of motivation to achieve the promised goal.
When the promise is kept, it gives rise to a sense of accomplishment, enlightenment or satisfaction in the person who received it. It appears as a reward, a light that illuminates the road to the future and gives meaning to existence.