From Longman Business Dictionary
motivationmo·ti·va·tion /ˌməʊtəˈveɪʃənˌmoʊ-/ nounHUMAN RESOURCES1[uncountableU] eagerness and willingness to do something without needing to be told or forced to do itSome of the workers seem to lack motivation.
2[countableC] the reason why you want to do somethingmotivation forWhat was your motivation for becoming a salesman?