I feel that depression occurs when the limbic (?) part of my brain (survival instincts) runs low. Then I ruminate WHY do I feel sad, then my thinking part of my brain thinks up reasons. But I have concluded that I am not actually sad (unless I create some sad thing as the reason) but depression for me is the inability to fight for life. If my heart or breathing weren't automatic, it would be easy to just die.

So this is where ruminating comes into play for me. To reiterate: Depression begins, brain triggers the questions "why am I sad" and imagination triggers reasons or memory.

But I think bipolar might be just that simple. A brain imbalance where sometimes we barely feel able to be alive, and other times have energy to climb tallest mountain.