You can invent an extrabadge for the occasion, where you run a "clean" mile/kilometer.... Today the extraordinary incident happened to me... I ran my third kilometer at exactly 6 minutes, zero seconds and zero hundreds of a second... The rare clean and tidy kilometer. My first feeling was happiness - the next was, that a badge for this achievement were needed. The possibility for running a "clean kilometer" is about 1 to 6000 so I believe that this would either motivate runners to do consistent training of a certain time for their kilometers - or they will feel surprised and proud of the achievement.