When people are motivated to do something it is either extrinsic motivation or intrinsic motivation. Incentives such as money is an extrinsic motivator to work for. A person may work for money because they believe that the money will give them the opportunity to buy something that the want. The worker will believe that putting in the work now will be worth it in the end when they get paid. Research states that as incentive values increase so does the motivation to attain the incentive. However research on intrinsic motivation proves that over time extrinsic motivation will be much harder to sustain rather than intrinsic motivation. Intrinsic motivation is when a person is motivated to do something even when external rewards are not guaranteed or offered. This type of motivation is discussed by many athletes as being crucial in sustaining long term success. This is because athletes get paid millions of dollars and it can be very easy to lose motivation if you have everything you want externally. The best athletes have intrinsic motivation to be the best, which is what keeps them going.