If we experience a fall, we must never let it get us down. Getting depressed is exactly what the Yetzer Hara wants, and it leads to a vicious cycle of continued falls. (Listen to this powerful 5 minute audio clip from a Shiur of Rav Ben Tzion Shafier).
The truest test of an eved Hashem is davka when Hashem takes everything away from him, such as when he falls and feels nothing; no emotion and no Hislavus. Hashem does this purposefully sometimes, because that's a person’s moment of truth where he can ask himself honestly, “am I an eved Hashem because it's my nature and/or because it keeps me emotionally happy, or do I serve the Almighty because that's His will and nothing else?”
The Lechevitcher Rebbe (a student of R' Shlomo of Karlin) once went as far as to say that even if a person just killed someone and the knife is still dripping with blood, and he feels unable to stand up and daven Mincha (the afternoon service) with all his strength and heart, then he has not yet tasted from the waters of Chassidus!
The Be’er Mayim Chayim says that in the army, when they would want to test a great soldier to see if he's fit to be a general, they would put him on a wild horse that was impossible not be thrown off of. The whole test was only to see how fast he would get back up after he was brutally thrown down and wounded.

even if we fall. DONT GET DEPRESSED that is actually the plans of the yetzer harah
this is actually the moment where one can yet still grow. where he shows that its not an emotional thing, rather its because its hashems will.
it is said that one who just killed someone and has the bloody knife but cant get up to daven hasnt drank the waters of chassidus. there are those who feel that they live a double life. one of addiction and one of an eved hashem. this is wrong, because as long as we are trying, we will always be an eved hashem, therfore there is never any reason to be depressed