Everything that I have read has said not to exercise too much but some is ok--I think that walking your dog (dogs need exercise too!)should be all right though. Obviously, if you begin to feel light-headed it is a sign that you should stop. I just started a juice fast today (I am not sure how long...my goal is to lose 20 pounds...my desired weight is the exact same as yours but I am starting at 140). I have decided to do some yoga everyday...I am hoping that it keeps me from being hungry too. I am definitely glad that someone else is starting at the same time!