DENVER | Her training runs involved pushing a jogging stroller loaded with enough snacks to keep her toddler content. Her core workouts featured exercises as her kids climbed on her back or even joined her . Her schedule sometimes got thrown off for potty training. This is the program that allowed Sara Vaughn , mother of three, real estate agent and burgeoning 1,500-meter runner at 31 years old, to earn a spot for the world championships in London this week.

