I've learned to work on each major issue. Depression seems to be a symptom of the overload. The depression will slowly but noticeably be reduced as problems are addressed.
Examples: For years I had stopped working out, I was drinking heavily for a couple years, I was overspending, and I was spending too much time with toxic people. Each small act towards the goal is in fact the goal itself. Each small start is the grand moment of change. I still feel depressed sometimes but not as overwhelmingly so.
It seems that once I address the situations that are the main contributors to my depression, I can see more clearly what is causing this response in me from life. I suspect as you said that it as a lot to do with upbringing. I wish I was closer to my siblings but the way we were raised makes it difficult.
One thing I have realized is that sadness seems associated with intelligence. It's smart to be happy of course, but avoiding sadness isn't
It does associated with intelligence in my opinion but I may sound narcissistic if I write it that way. Tho most of my friends disagree bout how intelligence may affect depression. It's either I am not as smart as I think or they are too dumb to see. But as a logical reason I might have to agree with it, if you look it from other side, there is so little of people with above average IQ(I am not sure of the numbers) thus making it hard to find someone who have the same vision, and witty minds :)