Most people tend to assume that they have a fixed amount of energy, motivation and ability for their work, and don't realize how much these can be inflated by positive emotions.
This is where a musician finds the perseverance to do the technical exercises that get her to playing a piece. And where a budding scientist finds the patience to work through a complex topic in spite of all the overwhelming conceptual hurdles. And where a programmer gets the motivation to learn arcanes of some obscure tool.