Forget the kettlebells, barbells, all the leg machines at the gym. Find a chair, find a wall and be prepared to work those legs!
Warrior III is THE pose (in my mind at least!) for finding strength, balance, energy and release tension from all parts of the body. That is not to say that it is easy, be prepared to be challenged. A key point here is that the first level of strength is NOT in the muscles, rather on the correct stacking of the bones. Think of finding a plum line from the center of the hips over the ankle joint and then allow the muscles to find the balance. Quads and hamstrings must work together, otherwise the battle within will end up with a winner and a looser. The floating leg has a similar connection, however, the glute complex is stabilizing the posture so root the foot into the wall and build on the awareness first.
Use props to get you there, the wall is your best friend, for a few minutes at least. The chair helps me to find a little more opening and activation behind the heart. A good 10 breaths here to find micro adjustments and consciously connect to the Pancha Vayus. Play with both side, accept the difference the wean your way off the wall, and loose the chair. This does not happen at once, remember it takes time, be patient and practice, practice, practice.
What does the mind speak to you in the pose? Like it or leave it? Something to grow into? Let this be your self-study for a few days and reflect, if you are on or off the mat. Journal on it, read about the pose, ask your instructor for guidance.
There is a great story that follows the asana series of Warrior I to II to III, about the "battle" of Virabhadra with the father of Sati (an earthly form of Shakti). If you are interested in learning about the amazing stories behind the asanas, consider following the link below to read my book review of "Myths of the Asanas" by Alanna Kaivalya & Arjuna van der Kooij: