stage four diagnosis

I recently developed what I thought was an exacerbation. I have had them before. I have had COPD for 10 years.
My doctor had me do a pulmonary function test. It was awful. My lung capacity has decreased.
So, he said I had stage 4. He didn't say much else except to take care of myself. No medicine, just continue my routine that I already do,
Does anyone else have any suggestions for exercises or anything else?
Thanks !