" Gallagher’s writing emphasizes that the content of what we focus on matters. If we give rapt attention to important things, and therefore also ignore shallow negative things, we’ll experience our working life as more important and positive. Csikszentmihalyi’s theory of flow, by contrast, is mostly agnostic to the content of our attention. Though he would likely agree with the research cited by Gallagher, his theory notes that the feeling of going deep is in itself very rewarding. Our minds like this challenge, regardless of the subject. "

― Cal Newport , Deep Work: Rules for Focused Success in a Distracted World