Sometimes the yetzer hara deceives you by telling you that you committed a grave sin when there was really no sin at all or [at worst you violated] a mere stringency. His intent is that you should feel depressed as a result thereof, and thus be kept from serving the Creator, blessed be He, because of your depression.

You must understand this trickery, and say to the yetzer hara: "I will not pay attention to the stringency you referred to. You speak falsely, for your intent is but to keep me from His service, may He be blessed. Even if there really was a degree of sin, my Creator will be more gratified if I do not pay attention to the stringency that you pointed out [to me] to make me depressed in His worship.

"In fact, I will serve Him with joy! For it is a basic rule that I do not think the Divine service to be for my own sake but to bring gratification to G‑d. Though I ignore the stringency you mentioned, the Creator will not hold it against me, because I do not pay attention to it only so that I will not be kept from His service, blessed be He. For how can I negate His service, even for a moment!"

This is a major principle in the service of the Creator, blessed be He: avoid depression as much as possible. - Rabbi Yisrael Baal Shem Tov, Tzava'at Harivash Ch. 44.

When we retire at night, we constructively review our day. Were we resentful, selfish, dishonest or afraid? Do we owe an apology? Have we kept something to ourselves which should be discussed with another person at once? Were we kind and loving toward all? What could we have done better? Were we thinking of ourselves most of the time? Or were we thinking of what we could do for others, of what we could pack into the stream of life? But we must be careful not to drift into worry, remorse or morbid reflection, for that would diminish our usefulness to others. After making our review we ask God's forgiveness and inquire what corrective measures should be taken. - Big Book of AA pg. 86.