Depression is a fog that settles in your soul, like the only part of a frightening old fairy tale that is actually a thing that can happen to you today. An arbitrary, pitiless enchanter's curse. It has no time or season. It can be provoked by pain, or by endless stretches of dark days without the sun, but just as often it emerges when the sky is clear, the sun bright, and you have "no reason" to be sad. Because depression is not sadness.
Depression is an evil fog that wells up within, wrapping itself around your heart, and everyone and everything in it. In the gloom of depression your entire world looks lifeless, monstrous, or meaningless. Perhaps all three.
Well-meaning outsiders look at you and see someone who's just sad, maybe someone who's forgotten gratitude, or someone who needs to "get out there" and "out of the self" for a while. Less kind observers might see you as merely lazy or negative. Though there are people who care about you very much in your depression, it is rare for anyone else to understand truly what you are living through.
When you are in depression, you still have perfect use of your intellect. You can know and understand so much. Even with the depressive weight dragging every thought through a swamp of meaninglessness, you know that some things are objectively good for you, like a walk outside, or washing your face, or eating something warm and nourishing. You may do none of these things: you know they are there, but there just doesn't seem to be a point. All of your WHYs have been swallowed up and lost in the fog.
A Why is a creature of indescribable color and light; it is powerful, swift, and graceful. Depression is one of the only forces on earth that can overpower it, but the Why will still try, in the depths of your soul, to break the curse and run free again. That is why, sometimes, in the midst of weeks of dead depressive fog, you will sometimes feel something: deep sorrow like the scent of burning leaves on a cold breeze. One of your Whys is singing, deep in the fog.
If you should catch even the smallest glimmer of your Why, follow it. Hold on to it.
Seize that glimmer and with it do one thing. Defy the fog.
However small, you will know that you and your Why did do something today.
The curse is not unbreakable. You broke it, even if only for a time.
I wish you strength and peace.