Steinbeck isn't simply urging confidence—he's identifying something harder: the difference between gratitude (which can become self-diminishing) and pride (which demands you claim your full worth). A writer grateful to be published might accept poor pay or editorial butchering; one roaring from professional pride sets boundaries. We see this daily in workers who apologize for asking fair wages, as though employment itself should inspire humility rather than mutual respect. His lion metaphor cuts deeper than generic pep talks because it names the specific poison: becoming so grateful for the chance to work that you forget you've earned the right to speak firmly about your own value.