This, but in my mind, exercise is anything that elevates that heart rate for extended periods of time, and takes place in your leisure time.
Studies have shown (I can link to some if you need me to) that physical activity during work (ie, manual labor) is not as beneficial as leisure time excerise (that is, working out in your free time).
Why would it not be? You're physically doing something. Power walking is also a thing and not that far off from jogging. Even more so if you happen to do it up hills.
