It is important to realize that jogging or running to lose weight is different that that for building your up your cardio vascular strength. When trying to lose weight, it is important to keep your heart rate in the fat burning zone and for cardio in the cardio zone.
A heart rate monitor watch is a very useful tool for monitoring your heart rate to ensure you are keeping yourself in the fat burning zone. Why waste the time and energy to run or jog if it is not burning away the fat efficiently?