There are probably special mobility aids for this sort of thing available at your local hospital.
If you can't get back up after kneeling, perhaps use a gardening kneeler. Most gardening/hardware supplies should have them. They look like an upside down padded stool.
If putting on your shoes is still possible and not causing you actual damage then accommodating your weight issue might be the wrong thing to do. Wouldn't it be better to put up with the discomfort and inconvenience for the next six months or so, using it as a daily spur for your weight-loss effort.
I'm sorry if I may seem a bit harsh, and I don't know your personal situation, so you may simply dismiss my suggestion as unworkable. However, I've found that with myself and other people, it's easiest to change personal habits if the short-term benefits of change outweigh the short-term pain of not changing. By masking the discomfort and inconvenience of your condition you may lessen your resolve to actually fix the problem.