UCs look for people that can contribute to their schools. They are like communities. I don't exactly think this fits that criteria. You should probably look into yourself for other qualities. Im am not saying your qualities are bad, but your taking your chances on this one.
here are my suggestions...
Im not the best of writers or readers so do of this as you will:
this sentence is too long and awkward, im pretty sure you can shorten it or split it into more sentences:
I secretly envied those who were confident of themselves and who believed that they were fully capable of becoming leaders to be in charge of others.
what do you mean by this?
Although my initial perception of confidence was perfectly and entirely positive, as I became more aware of their excessiveness, I realized that it was not so.
If you can give examples and try to be concrete with what you say.
My rather quiet personality aided in various aspects of my life by making me a modest person who knew what to do at the right moment.
what were these aspects that were aided?
what is a right moment?
you talking about yourself and that's it.
give back up to what you are saying.
Christopher Rafael Arciniega