Light but good burning excersise advise!!

get0fit0freak

Ok I have arthritis, bone spurs, muscle spasms and degenertive disc disease. My dr suggested low impact excersise. I walk 5 to 8 miles 5 times a week. I am afraid my body is going to get used to this and stop helping me burn calories. Can anyone give me some advise on what kind of excersise that will work In the last few years I have lost over 100lbs in the last 6 months I have lost 50 of that I need to loose this weight I am so excited and I AM determined. Thanks for any advise