Most people don't stretch, because, in a way, it's one of the activities that hurts us the most. It's instantly uncomfortable, which isn't true when you work out intensely and can build up to that pain, or when you have sore muscles from a tough session the day before. If you watch football players stretch before a game, you see a kind of agony on their faces that you don't see when they're on the field. This pain is why yoga incorporates so much breathing, because you have to exhale that discomfort out to get through it. And mentally, yoga is a good way to practice being uncomfortable, because for many of us who are used to constant action, it's challenging to have to be still and focus on the body and breathing.