Playing. Playing is better, even if I like to watch, because it involves you and prevents you from thinking about anything. When you watch sports, it's easy to get distracted, but if you play sports, you have to be completely mentally and physically, get away from the real world and relieve stress. Being so physically active is such a nice feeling. After a game or something, you will feel much better knowing that you have worked, compared to sitting on the couch stuffing your face.