A friend of mine showed me a device that i believe bring a disruptive breakthrough in the way you jog. Garmin, brought to market a GPS watch that tracks your move and can tell you very precisely how well you are performing, what path you have followed in a computer map, if you are speeding up or speeding down. Even better you can create a virtual companion (speed, level,…) and know at each second how you are doing compared to him! a real way to improve your performance