"I wasn't born with any innate talent. I've never been naturally gifted at anything. I always had to work at it. The only way I knew how to succeed was to try harder than anyone else. Dogged persistence is what got me through life. But here was something I was half-decent at. Being able to run great distances was the one thing I could offer the world. Others might be faster, but I could go longer. My strongest quality is that I never give up."
— Dean Karnazes (Ultramarathon Man: Confessions of an All-Night Runner)