On a daily basis, people tell themselves that they are going to get fit and run more. However, people often struggle with getting started and learning how to run as they do not know how to pace themselves, often overexerting themselves in the first five minutes. We have developed PaceKeeper, an app that integrates the heart rate monitor of the Moto360 smart watch with Android devices. PaceKeeper keeps you on track by calculating your ideal heart rate range that should be maintained during your run and changing the tempo of the music accordingly. The Moto360 monitors your heart rate in real time so when your heart rate falls below the calculated range, PaceKeeper speeds up the current track playing; when you are running too fast, the music slows down.