Are people primarily motivated by internal motives or by external events

Motivation arises from both internal motives (i.e. needs, cognitions, emotions) and external events (i.e. incentives, consequences, social contexts).  Is one of these sources of motivation more potent or more effective in motivating people than is the other?  Are people primarily motivated by internal motives or by external events, or are people motivated about equally by internal motives and external events? Justify your response by giving examples from your own life.