need to get fit

Agree with walking, do a bit more each week as you are able.
You could also ask your Dr if theres a community gym nearby where they specialise in older people or those recovering from injuries. the point is they have more expertise and can advise you better by selecting appropriate exercise. The advice of a nutrutionist if you have a free one could also help.

Swimming is also a good one as it supports your bodyweight.

Theres nothing special about the MFP way or at least theres no secret, the power to lose the weight is in your own hands by eating at a deficit and moving more for a sustained period of time. You either stick wit it or you do not. No gimmicks just plain old burning more than you consume.

Do you have a local pool that has water aerobics or deep water toning? You don't have to be a swimmer. The water eases the pressure of gravity but also gives you great resistance as you move around through it.

Get a good areobic mat or pad of some sort and put it in your living room and walk in place, maybe using some light hand weights. This way you can watch TV or read a book while exercising and when your feet start to hurt, you can take a break.
To reduce your weight, it's about how many calories you put in. Maybe start by just focusing on your food choices. As the weight comes off it will be much easier to move. I know I have bad feet as well. They tend to start going numb then feeling like I'm stepping on a thousand needles. As the weight has come off, the needles have reduced.
What ever you decide, just start now. Not tomorrow, not on Monday, start now and see it through.
Best of luck!