This is a simple posture with a simple mission. The Tree Pose improves posture and balance and increases the flexibility of the ankles, knees, and hip joints. By strengthening the internal oblique muscles, it prevents hernia. This is also a preparatory posture for the Locust Pose. This is a good posture to work on balance and locking your standing knee. Although it is tempting to bring the hands in prayer, it is not necessary to do so in order to achieve the health benefit. It's better to hold the foot at the hip joint, than to let the foot slide in order to bring the hands in prayer. Lastly, "you can mess with the Gods, but you can't mess with the knees." Take your time, feel out the posture, and back off if you feel sharp shooting pain. Be fearless, and not reckless!