What makes Nin's observation unusual is that she's not simply saying brave people live fuller lives—she's suggesting our lives are *literally sized* by our choices, that timidity doesn't just prevent adventure but actively shrinks the very space we occupy in the world. Most of us assume our circumstances determine our boldness, but she reverses it: our willingness to take risks fundamentally alters what's possible. Consider someone who stays in an unfulfilling career for twenty years because speaking up feels risky—they don't just miss one promotion or opportunity, but watch their entire sense of what they're capable of gradually diminish until the smaller life feels like all there ever was. Courage, by this reading, is less about dramatic gestures and more about the thousand small refusals to accept unnecessary limits.