Young sustained a concussion and whiplash in a car accident before last month's NBA draft. The Celtics chose the 6-foot-6 swingman 17th overall with its second first-round pick but held Young out of practices and the competition for young players and free agents in Orlando.
Young said Tuesday that he was cleared to practice a "few days ago," adding that the scary rear-end collision showed him "how fast things can change. It really opened my eyes about things and I'm very blessed that I'm here and still playing."
Information from The Associated Press was used in this report.