I have to admit, the exercise part of dieting was a real barrier to me when I was morbidly obese. And it wasn't that I was being lazy! Just strap a 30kg bag of sugar to your back and wear it all day, every day and see how 'energetic' you feel! As the weight came off I found I was naturally doing more and more. Later, worried about floppy bits, I joined a gym and did weight-lifting exercises. My weight loss did not accellerate as I worked out, probably because I was putting on muscle which is heaver (but smaller in size) than fat. It was a strange experience staying the same weight and finding I had to constanly hoik my once tight pants up.