JOHN-hello and welcome to OH ! You will notice the site is called OBESITY HELP..not Obesity SURGERY Help..You are absolutely welcome and encouraged to post here..whether or not to have surgery-of ANY kind-is a very personal decision..
I'm sure most all of us can identify with your exercise woes, on one level or another. For me, it was just GETTING STARTED. Unlike you, I WAS self conscious..going to a public gym/pool was HARD...KUDOS to YOU !!
As a 35 yr nurse, I do agree I'm a bit worried about the medical stuff, but I certainly understand the $$ of healthcare. Start exercising SLOWLY-and if it truly HURTS (not just sore, from using new muscles), then STOP!..Like others have said, walking/running in water is a GREAT work out and will burn a ba-gillion calories!
Not too sure about the accuracy of your "bathtub weighing"..lol..If you truly need to know your weight, vets and feed stores have large scales. My son works at a feedstore, and they have a scale that goes to 750 lbs, that people can stand on.
DO be sure to get enough protein/veggies/FLUIDS to support your added activities..
Anything else we can help/advise you with, PLEASE do not hesitate to ask !