Are depressed Christians on medication still able to find joy?

I can't. And I feel so guilty about not being an estactic lover of Christ...why can't I jump for joy to be a child of God? Why doesn't the scriptures uplift me out of this abyss? How do I stop feeling guilty about my depression...and yes, I am on Zoloft. I still have trouble getting out of bed sometimes or finding the motivation to be active or devoted to an activity. Am I just not strong enough of a Christian? Am I lacking in belief or faith or obedience? Explain. Give me some scripture please.