What about swimming pool activities?

Exercising is a great way to raise your metabolism temporarily and improve effeciency, as well as a buffet of other benefits. Anything you can manage would be a start. Do you have a physio or a specialist who can advise/give you a suitable exercise program?

Of course diet is VERY important in weight loss. If you're carrying any significant amount of weight and having trouble losing it despite a healthy diet, then maybe see your doctor to check things like your thyroid activity