I am so sorry to hear about your husband's cancer. It's shocking to hear that you have cancer but very confusing when the medical profession can't find the primary site. Pulmonary rehab is wonderful. It was like a whole new world opened up to me! I can now walk up and down the stairs without sounding like I'm in trouble. People with every type of lung problems were at mine. It was my pulmonologist who recommended it. Perhaps ask your doctor if your husband is ready. There need not be any time caps - like a year or six months. Some people go early on and others, like me waited. Please let me know how you make out. PS: There were also people there who were on oxygen!