Yoga is a practice. You might be practicing your balance, flexibility, strength or perhaps it is mindfulness. Yoga is not a single practice. The more you practice yoga, the more you recognize the universality in life.
Harmonizing your mind, implies that you learn how you think. You explore how you interact with the world and yourself and how those interactions shape your emotions. In yoga terms, you cultivate Yama. Yama is narrowly translated as ethical guidelines or restraints. In reality, they are a set of universal practices that are fundamental habits of the mind. The 5 principles are a means to be aware of the instinctive patterns of the mind and to move them towards compassion.