ATLANTA — Jason Russell, a digital project manager, husband, father, and a founder of the global fitness group Black Men Run, was on top of the world when a debilitating stroke derailed him several years ago. Since then, Russell has fought to return to life and fitness, and on Independence Day, he accomplished a major feat: completing the largest 10K race in the world. Russell was among members of Black running groups from across the country who descended on Atlanta for the Peachtree Road Race on Thursday.