Ellen, I agree with Liana...walk around your house as much as you can. Eventually it will get easier. When I had heart surgery, the doctor told me to walk in my house for 15 min, 3 times a day while recouperating. I went down the middle hallway and back up, around the circle through the living room, dining room and kitchen, then back up and down the hallway again. Boring, but effective. Since you are a retired RN, you know to make sure this is ok with your doctor, that you don't have any underlying medical problems you don't know about. I say I'm 5'4" but I'm really 5'3" and I started our around the same weight as you. Although it hasn't come down a lot, there's a big difference in how I feel. You really will be avoiding some serious health problems by doing whatever exercise you are able to do and losing some weight. They say that 10% of your weight will make a big difference.
Good luck to you. You can do this! You have your own coaching system right at home with you!
IF not now, when?