Breathlessness after a Lobectomy

I had a lobectomy mid October, and then a second surgery in November to repair an air leak. Since then I experienced a lot of shortness of breath. My doctors are surprised at the extent of my breathlessness (I have to use a shower bench as it’s difficult to stand fore the entire shower), and frequently have to sit down to rest before I can continue walking. Has anyone else experienced this after surgery? What did you do to alleviate it? And, did it eventually go away? I am going to start pulmonary rehab next week. Betty