The Five Elements in Nature
Winter is the energy of the element Water, the time of rest and hibernation, when nature retreats to build up its reserves for its next cycle of seasons. This is a quieter, more reflective time of year, a time when it is easy to sleep in, stay at home, and let ourselves rest.
Water is about our ability to flow and to overcome obstacles.  To understand the attributes of water in ourselves we can think of the many ways water presents itself in Nature. 

Think how our energy can resemble a mighty river or a trickling stream, the waves of the ocean, a frozen lake, a gentle rain.
Water is the energy of the Bladder Meridian, the "Official in Charge of the Reserves of Energy". It is our ability to keep going or a feeling that we are too tired. 
Winter and Water
The more we rest in Winter the more harvest we can expect in Late Summer.
The Kidney Meridian is called " The Controller of Water" and, as we are 83% water, it is an important function.  It is also in charge of the Essential Qi that we inherit from our parents that controls the bigger cycles in our life like puberty, menopause, etc
Water is the realm of fear, drive, ambition flexability and will power.
Spring and Wood
Summer and Fire
Late Summer and Earth
Autumn and Metal
Winter and Water