For you guys with hurt backs, I have been through some of that as well. I have had 4 back surgeries. My L1-5 all severely ruptured. A while back I lost 100 pounds and then ruptured another disc making me unable to walk until surgery. I gained it all back and about 7 months ago I decided I needed to do something despite myself so I have done Keto. When I can I do Yoga and walk even though its not far before the pain swells up too much. I am down 105 lbs again. Sometimes like this week when I can barely walk I jist do stretches every day as much as I can bear it. I will do some yoga poses that I am able to get into and out of. It is hard to develop habits when what you are able to do may change day to day or week to week. I try to develop habits I can do at least some part of. If you have access to an indoor pool I find that is one of the lowest impact exercises I can do personally. I know everyone is different and it gets exhausting when people suggest things and you are like "they don't understand how hard it is for me to do x" Just my 2 cents.
Also, I know they are expensive and Im not saying there isn't something that may suit you better but I got a sleep number bed that raises at the head and feet and it has improved my sleep immensely. Your whole body is shit when you wake up 3 or 4x and cant go back to bed because of pain.