or http://pss.sagepub.com/content/21/11/1686.short

A theory I call demands theory is a little more nuanced. Willpower is a limited resource that gets exercised whenever we are overcoming psychological resistance to fulfill demands. What Carol Dweck demonstrated in my view is that its quite easy to frame context differently so that there is less psychological resistance toward doing a task. This means you won't have to exert your limited willpower resources.

To give an example, if you believe something will be fun, you will have less mental resistance toward the activities, so you will last longer. If you feel like something will be hard and unpleasurable, most people won't last as long as they use up more willpower to continue. The trick then is how can people adjust their mental orientation toward their day to day activities in such a way that their will power is maximized.

Or in 3 words: work as play.