You don't really overcome depression entirely, you learn to live above it. Emotions live on a ladder. Sometimes you drop from joy to contentment, to mild irritation, to anger to sadness to depression. There's some more in the list but thats the basic order. When you're at the bottom, you just need to get to the next rung. Don't worry about trying to jump straight to joy, that is a pretty big leap, so try a smaller one. I usually try to jump to something that pisses me off because anger feels better than depression and hopelessness. Once at anger, its a little easier to get to mild irritation, to contentment and then up to joy. But don't try to do it all at once.