If you want to conquer fear, do not sit home and think about it. Go out and get busy.
The genius here isn't simply that action beats worry—it's that Carnegie understood fear thrives in stillness and silence, where your mind becomes the architect of catastrophe. A person lying awake at 3 a.m. rehearsing a difficult conversation will suffer a dozen imaginary rejections, but the actual conversation, however awkward, rarely matches that fever dream. The quote works because "get busy" means purposeful engagement with life itself, not mere distraction; when you're genuinely absorbed in meaningful work or learning, fear loses its audience. Notice he doesn't say "face your fear directly"—that can paralyze—but rather step into the world with intention, and your nervous system gradually recalibrates what's actually dangerous.