I had a vehicle accident and penetration into my chest that collapsed a lung. I was in the hospital for 5 days and riding my bike 5 days after that. The doctors said what really helped was doing exercises on this device they gave me. You suck on it and see how high you can get the ball to go. I did hundreds of repetitions per day.

edit - I think they kept me in the hospital for two days too long. They just wanted the insurance money at $4000/day.