Failure entered the world through the Knowledge of the Correct and the Error. Therefore if you can believe that the mistake was supposed to happen, Then your Joy will be saved from the Joy Thief. Those that do not believe that the mistake was supposed to happen enter into Denial - Anger - Depression. Yet return to Joy when experiencing Acceptance.

And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption. (Ephesians 4:30 NKJV)

Through faith one can find the peace and cast of anger.

Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice. (Ephesians 4:31 NKJV)

For you can judge a tree by its fruit.

You will know them by their fruits. Do men gather grapes from thornbushes or figs from thistles? (Matthew 7:16 NKJV)

Meaning you can judge anothers faith by their emotions.

Beware of false prophets, who come to you in sheep’s clothing, but inwardly they are ravenous wolves. (Matthew 7:15 NKJV)

But without faith it is impossible to please Him, for he who comes to God must believe that He is, and that He is a rewarder of those who diligently seek Him. (Hebrews 11:6 NKJV)