From Longman Dictionary of Contemporary Englishmotivatormo‧ti‧va‧tor /ˈməʊtəveɪtə $ ˈmoʊtəveɪtər/ noun [countable] something or someone that makes you want to do or achieve something → incentive Money is a good motivator.
Examples from the Corpus
motivator• Like Kev says I rate him highly both as a defender and a motivator.• As a special-teams coach, Tillman was known as a motivator.• Moseley thinks the defeat will serve as a motivator this week against Washington and Washington State.• This could be a disadvantage but sometimes served as a motivator.• Money is a good motivator.• Fear, as we all know, is a great motivator.• Status can be an important motivator.• The other motivator could be violence on the streets.• Sales team motivators and psychologists agree that if you want something to happen badly enough, you can make it happen. 