You can't enjoy anything when depressed. Stuff that you previously loved you can't be bothered to do any more.
That's a succinct summary.
Here's a metaphor that might help more people understand depression.
Imagine that you are walking in a narrow alleyway.
It's cold. Not spectacularly cold, just cold enough to be unpleasant.
It's raining. A drizzle. That apathetic rain that gets you thoroughly wet.
The alley floor is pitted, grey, dirty, slimy.
The walls on either side of you go up many storeys, blocking out all but a thin strip of sky.
The alley walls are pitted, grey, dirty, slimy.
They are also featureless. No doors, no windows, no change.
That strip of sky? It's grey. Always.
You walk.
The alley does not end. It goes right round the world.
You won't know when you get back to where you started, because everything is featureless.
The alley is effectively endless.
You walk.
You know that everywhere else is the same. This alley is all that there is, all that there ever will be, anywhere.
You walk.
It's just as cold as it ever was, and ever will be.
It drizzles, like it always has and always will.
You walk.
The walls are grey, slimy and featureless, as they always have been and always will be.
The ground is grey, slimy and featurelss, as it always has been and always will be.
You walk.
You can stop walking. Eventually, you will stop walking.
That's death.
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