One of the constants in the world is change, which is not constant at all. Change happens everyday, every moment. Yet, we as humans are constantly fighting change, fighting, and trying to hold on to a moment. All of this tension with the inevitable creates an unbalanced existence.
The concept of Yin and Yang is a concept of change. Nothing remains the same, everything is in constant motion, like the seasons. The Yang represents the active energies, the Ying represents the quiet energies. Yet, in each side, there is a circle of the other - for nothing is entirely Yin or Yang.
Like us - we are neither Yin or Yang entirely. Some days we may be more Yin, some days we may be more Yang - but there will always be some of the other showing.
When you understand Yin and Yang, when you understand that everything is in constant flux, and you stop fighting it, instead except it.
So how does all of this apply to Feng Shui? Applying a balanced approach to our space creates a supportive environment for us to live in.
For example, some rooms will be more Yin (quiet), such as a bedroom. And - some spaces will be more Yang (loud), such as a living room.
Understand which rooms will benefit from being more Yin or Yang. Understand that like the seasons, change will happen - so it's OK to adapt our spaces to support those changes. Balance and Change.