Dear NA,
Most patients are discharged from the hospital 5 to 7 days after uncomplicated bypass surgery. The recovery time at home following that is usually 2-4 weeks before resuming work. After this the continued recovery may last 6 months to a year before feeling back to 100%. Sometimes incisional pain may persist for quite some time. If it continues to be a problem a chronic pain specialist may be consulted.
As far as the lungs usually no specific therapy is necessary after hospital discharge unless his doctor has recommended otherwise. The breathing exercises in the hospital are designed to avoid in-hospital complications such as infections and poor air exchange.