Shadow

Sometimes it's small and non-intrusive. It follows you around quietly without an argument. You hardly notice it exists. 
At times it's bigger and more pronounced. You see it when taking photos under the bright sun in short winter afternoons. It's stepping in in front of you to make a point.
And then the time comes when it starts to hover above you where it's getting harder to ignore it. It covers your sky, just a small part at first,  then slowly spreading like a big stain and taking away the sun and the sky, taking away warmth, light, color,  playing with your mood and finally getting your full attention.
It starts sipping through your pores, getting inside even deeper. You are suddenly very aware of the probing intruder searching for something with its alien fingers. The cold is invading you like a doubt, occupying your waking thoughts, not allowing to forget its presence even for a minute...
till the next sunny day that is suddenly here washing away all the dark spots, braving in like a hero on a white horse to set you free. 
When all the pieces are falling in place you will recover and when you stop looking over the shoulder you'll be able to anticipate what's ahead and enjoy the ride.