I SOOOO agree with Coach Nancy and Archi. I had walking pneumonia years ago-- it is important to listen to your doctor and get lots of rest. (Just going downstairs to the living room, from my bedroom upstairs, had me lying on the couch for at least 30 minutes to recover from the effort.) Everybody's case is different-- I don't remember how long it took to recover or anything. All I know is that I did exactly what the doctor told me to (and I did not do what he told me NOT to do), and I recovered.
It is no time to be worried about exercise-- your number one priority is doing everything you're supposed to, for your body to heal from the pneumonia.