Many a times, we "fail" in our tasks. For example, I had a recital on the 25th of August and I messed up my piano piece terribly (to myself, at least. I think those present at the recital could affirm that). I admit that I had an attack of the nerves, and that made my fingers even more sweaty than usual. My fingers were cold too and were stiff so I could not play as fast as I usually would. I couldn't forgive myself for a few days after that and when people approached me to say that I played well, I sort of told them that my playing was actually horrible.
Now that I reflect on it, I actually think that the recital was a blessing in disguise. Before the recital, I was quite complacent in my practice and the recital actually motivated me to practice harder for my upcoming Grade 8 piano exam on the 10th of September. I experienced a change in my playing and now I'm glad that I messed up in the recital! If I didn't, I wouldn't have experienced the wake-up call and probably would still be slack in my practice. Definitely a NO for somebody taking his Grade 8 exam in a few weeks!
I haven't taken my piano exam yet, so I don't know what my score will be; but hopefully, I can get at least a merit.
I would end with a quote in Tengwar Quenya (Elvish language in Lord of the Rings)
It means, "Failure is the mother of success."