While Amber rates walking as major exercise and we can giggle at that, it's still a good thing for her to practice and work on since staying mobile is very important. And the way she talks about walking, she's barely hanging on to it as an ability, to the extent where she needs to practice it and set goals, steps and timers, and to talk about it a lot. She should just focus on dropping weight immediately anyway since her joints will only be shot more to shit by more activity, and she runs a risk of injury that could end her life in a chain of unfortunate events. It's why the weight loss doctor set her a low-calorie diet and nothing else - it's the safest way to begin. Fat Amy likes to talk about 'getting her heart rate up' through exercise but at 460+lbs, maybe don't do that, yikes. There's always time for exercise and muscle building at a lower, safer weight. The amount of movement someone like Amber is capable of is a pretty negligible calorie deficit, and staying upright and mobile is more important. Pure calorie-cutting is a very valid first step and it's not mythical at all, anyone honest about fitness is going to tell you what you eat is the most vital component for weight loss.