In my psychology class I learned that depression is feeling hopeless. We feel depressed when things are not going our way or how we wish. It feels hard to believe that what God is helping us when everything keeps getting worse. I have been there. It is a sad time.
I felt sad and weak a few weeks ago, and the way I came out of that was trying to see all the good in my life (being thankful) and by thanking God for all he does, for listening to my prayers and for being this being of pure love (praise and thanksgiving).
Things became easier after that. My faith will be tested again, just like yours will. Try to focus on what's good in your life, whatever that may be: your healthy smile, your beautiful kids, the car that takes you to places faster than the bus/subway.... and then take the time to thank God for creating another day, for giving you hope (if he didn't you may have killed yourself or sold your body), for being Him, for being love, for being happiness, for being merciful, for being God