Warrior Series: Warrior II
From Warrior I, keep your heels in alignment and your front knee bent. Turn your hips and shoulders to face the long edge of mat. Your bent knee should be tracking back toward your little toe. Remember to keep the front knee directly over or behind the ankle. Never let the knee drift past the ankle. Bring your arms parallel to the floor and reach out in opposite directions with your fingertips. Relax your shoulders down, and align your ribs directly over your hips. Lift up through your upper body as you sink down into your hips.
To decrease the intensity, slightly straighten the forward leg or shorten your stance. If you typically have shoulder discomfort, you can try bringing your hands in to a prayer position instead of keeping them parallel to the floor. No pose should ever feel painful – if it does, stop.
For getting into Warrior II from Mountain pose check out this article.
Warrior II is typically used in a sequence of poses. It can also be used by itself to strengthen the vastus medialis (inner quad muscle) of the forward leg. According to wiki, this pose:
Tones the leg muscles.
Increases flexibility of the back and legs.
Contracts the abdominal organs.
Prepares practitioner to do the advanced forward bends.
This pose is great because it builds power in the major leg muscles (quads) while also strengthening the stabilizer muscles for balance. If you keep your arms out, it also tones the arms and shoulders.
Be a warrior, not a worrier!