LOTS of hard work, feeling like you're going to vomit, is required, but hell is it satisfying when you see the weight melt off.
Yes, it CAN be done with a brisk walk/slow jog - BUT the heart rate has to go up, stay up, and you have to go past the point of feeling 'a bit uncomfortable'. Not sure what is hard to understand about that????
Everyone would agree that you have to go out of your comfort zone, and actually put the effort in, but when talking about sustainability and maybe even common sense, the unfit and overweight should be gradually building up to an intense exercise program.
Makes me laugh though, we are all horse people, can you imagine the row if someone suggested that the best way to take weight of their horse was to work it until it is dripping in sweat, and then do some more. When we are talking about horses we are (nearly) all agreed that lots of walking and trotting, starting with small amounts and building up is the way to improve fitness and take off weight. Well guess what, we are animals just the same and the same rules should apply to us.