I agree that yoga is good for my mind and my body. While doing yoga I can certainly improve my body by building muscle and improving my flexibility. It is also a good way to improve focus, concentration and will power. The stress reduction is good for your mind and your body because they both work better when you are relaxed.
Biking, running, lifting weights, push-ups etc. are also good for the mind and body but yoga, tai chi, qigong are better for becoming more aware of the connection between your mind and body. They are also better for teaching a person how to relax at will. The main difference with the healing exercises I mentioned is that they can leave a person feeling very relaxed and energized. I also recommend meditation. Even though you just sit there it is good for both the mind and body.