A few weeks ago, I could feel the depression setting in, and several runs that started with 8 minute miles didn't seem to stop it. So I resolved to go faster (read: got pissed and sprinted), ran a 6:21 mile (my fastest since I started measuring last year) and it was like spring cleaning for my brain.
Solvitur Ambulando, it is solved by walking
This is really interesting, in my martial art, which I did extremely actively in my youth - but far less now -- one of the sayings is "Keep walking" and "Keep moving"
The "Keep walking" is even used in some of the learning of actual techniques -- you move into a certain position with your Uke, and then... keep walking... and it executes the throw.
Keep walking is also used when talking about meditation in their teachings as well... movement meditation.
Even when my brain's biochemical state is fucked and broken and makes me want to hide and disappear, I can remember that it will change and I will feel better and that I do have some degree of control over it. You seem very self-aware, which is an enormous challenge when one is depressed. That means that you have one of the tools to escape depression. Remember that.
It may sound trite, but fuck it. Just keep on going. You will feel better.
Edit: If you can, try to find a professional counselor or psychiatrist. If nothing else, they're exceptionally good listeners.
I haven't been doing either recently, and my depression is really bad right now.
I was biking a lot, until my bike was stolen recently. That added to my depression...
But I walk an average of four miles a day, and take average of 10,000 steps a day and climb an average of ten flights of stairs a day.
My legs are still incredibly strong - but I need to do more about my depression. The last few weeks have been as much as I can take.