Throughout my life, I have been followed by a ceaseless onslaught of adjectives being attached to me from a variety of different sources, seeking to label who I am as a person.
^Remove this. Why would anyone who is expecting to read about yourself in three words care that you have 'been followed by a ceaseless onslaught of adjectives'. By the way, if you want this sentence to suggest that many people describe you in wonderful ways, remember that there are also negative adjectives, such as 'lazy, pathetic, ignorant, dogamtic' etc. In fact, I as a reader, could immediately assume that these words belong in the list of endless adjectives that people have used to describe you...
*Remove the first sentence. It is uninformative, ineffective, useless and potentially misleading.
However, as I now sit thinking of three words that describe me best, I realize that I would use none of these meaningless words, which are thrown around far too often, because I do not feel they adequately represent me and the spirit I carry inside.
^Again, just get to the point. You have 500 characters, and you are wasting them with irrelevant and unimportant information. Just answer the essay prompt.
Instead, I choose to illustrate myself as the embodiment of three of the fundamental classical elements that have carried great meaning and power since ancient times: earth, water, and fire.
^Earth, wind and fire are words. (They are also a disco band).
These words neither describe you, nor answer this part of the essay prompt:
three words that describe you best and tell us how you will use these qualities/characteristics to contribute fully to the BU community.
^Remove nearly everything, or maybe even everything, and try again. That is my advice:)