Often, the first draft is not the essay you originally envisioned. You might even discover that your ideas about your theme have changed as you have been writing. If you do not like the way certain sections are stated, re_arrange them. Once you are pleased with the body, make sure the conclusion and introduction still match it and complement the way you see your topic at this point. If not, rewrite them to fit the essay you did write and the way you see your topic now.
But you've got to sound: Like you care a lot, and like you're completely devoted to it. An example: "I am completely devoted to medicine for the rest of my life. It's everything for me because it's the only thing that's going to allow me to express who I am personally and professionally." High_impact language has this very strong absolute, emotionally rich, concrete side to it where as a reader I am completely engrossed, engaged, enmeshed. I buy it. I believe you. Some of the best places to look for this kind of writing is where there is someone who is making a very impassioned speech. One of the best places that I know is in the most powerful, compelling, moving speeches of our time. Like Martin Luther King's "I Have A Dream," or speeches by Gandhi, or speeches by John F. Kennedy, or speeches by Barack Obama. Speeches that really elevate you and make you feel that there's hope for you, hope for us and that there's something bigger to strive for.