I think this is right, no one is content all the time. Not everyone is A-ok 100% of the time. However it's hard to hold an emotion forever, specially when your mind is busy. I think its hard to maintiain goals etc when you're depressed (even though we have a tendency to forget our emotions when busy).

Fortunately depression doesn't always define a person's life. And people often have happier moments as well.In my experience depression didn't make me lose sight of my goals but it certainly didn't make me motivated or feel passionate. It was a case of fake it till you have it.
So I kept up school to a degree, ran kept some fitness... Not because of passion, but because if I kept it up maybe something good might happen.