Depression or any similar imbalance is just a signal that you have programs that contradict each other. Your beliefs (probably subconscious ones) don’t line up with your desires and they are pulling at each other. So change your beliefs or change your desires.
It’s helped me so much to realize that thoughts dictate emotions and you ARE in control of your thoughts even when you can’t control your emotions. It’s all about where you focus your attention. You don’t have to pretend the unfavorable circumstances don’t exist, that’s foolish, but don’t focus on them except when you can do something about it. I know, easier said the done, right? So brainwash yourself so no one else manages to do it.
Thing is...I think it goes beyond thoughts. When it' an unconscious depression , when it's physical (though I understand your POV, body and mind are one in the same). After experiencing what I have lately - during pregnancy specifically, I definitely believe that our genetic/chemical make up plays a big role.
I've been meditating nightly, life is going great - actually about to embark on a 6 hour road trip to collect all sorts of baby goodies from a hometown friend - yet, my depression (not today, but overall) has been at a level worse than when my dad died - maybe on par with what it was as a child when my mom died (I mean, with that total paralysis component).
There is truth in what you say - even when that depression hits - I mean, as I felt it and wrote this piece, I was focusing on writing, not on how I was feeling. Staring into space thinking "OMG Woe is me, I'm so depressed, I'm so depressed" definitely doesn't help lol (am I guilty of it though...yes).
Also - what you talk about above - (I'll put it into the meditation/reprogramming category) - clearly can change everything. I also believe that controlling emotions (though we both know it runs deeper than that and are probably saying 'controlling emotions' for simplicity sake') can change our chemical make up (along with what we put in our body), which in turn can change our 'moods' and 'states of being'.
Of course, again, it takes time - and a lot of it. And while in the middle of a deep depression - the kind of apathetic one where you lack energy to move - changing mindset or any kind of awareness seems impossible - so it's a bit of a catch 22.