I find it interesting how incentives influence motivation. I am very into fitness and consider myself in decent shape. I am currently in the process of joining the Air Force and the specific job I want to do is very physically demanding. I consider this a strong incentive to get myself in better shape. Incentives like this are great ways to stay motivated to achieve the goals you've set for yourself.
This also relates to willpower and rewards. If I am able to have the willpower to get out of bed in the morning so I can get to the gym and train I will only be getting closer to my goal. And the reward for achieving that goal will be qualifying for the job I want to do so badly.
Now after writing this I realize I have not had the willpower to do this as of late. The previous paragraphs have, in a way, reignited my motivation to train so I can get this job. I am determined to be fit enough to qualify for this job and I only have myself to overcome.