Source identified1
“It recalled to life my crushed self-respect, and my self-confidence, and inspired me with a renewed determination to be a free man.”
Douglass describes confidence as something restored through resistance: the change is not abstract positive thinking but a renewed sense of personal agency after physically resisting the violence of enslavement.
Source note: Life and Times of Frederick Douglass, Project Gutenberg #71893, in Douglass’s retrospective account of resisting Edward Covey. The passage belongs to the history of slavery and self-emancipation; it should not be reduced to a generic motivational slogan detached from that violence.