McBuff:
My suggestions are in red:
...
(I don't like that you start out putting yourself down. I understand where you're going with it and the point you are getting across, but you instantly set a low first impression) It is embarrassing to say that I was once a mediocre person who put forth the minimum effort required to succeed, however (no comma) over the last several years (no comma) I have matured and my priorities have improved. Having experienced the world outside of the protective nature of school walls has opened my eyes to the perils of mediocrity. Many people capable of great things settle for less, however I have decided to not be one of them; I now hold myself to a standard on par with my abilities. Physically, I partake in regular exercise and adhere to a healthy diet. Morally, I value integrity, honesty and dependability and my actions echo my beliefs. (Examples of how you value these would be good) Professionally, I continually educate myself, and aim to be the best in my workplace. Through research, I’ve found that these are all traits exemplified by the United States Navy’s core values and wish to be among other Officers with the same high standards. (I know what you're saying, but from this it sounds like enlisted don't have those values. This might not matter, but it came to my mind.)
I have worked hard and am proud of all of my achievements, the greatest of these being my licensing as an EMT-Paramedic, following completion of my degree in xxx from xxx. As the commander(no quotes, downplays your importance) of an ALS ambulance, part of my responsibilities involves supervision of all elements on an EMS call: management of police, fire, EMS and bystanders, in addition to treating potentially dieing patients. This overall scene management is the most challenging, yet the most rewarding aspect of my profession. I enjoy taking control of a time-sensitive situation and overcoming any obstacle encountered. This desire to lead is a primary motivation for seeking a commission in the United States Navy.
One final reason for my desire to serve is my longing to be a part of something great, in which I can take pride. This is one facet missing from my job. Medicine is rewarding, however frequently I find it to be an individual effort. I feel that when I wear my current uniform, I merely represent myself and wish for something more meaningful. It would be an honor to put on a uniform that represents 300 million people, over 225 years of tradition and the freedoms that I, as an American, have been blessed with.
I like yours a lot dude. Especially the closing. My suggestions are merely that, so take what you like and no what you don't. Just don't ever downplay your importance or put yourself down. You may also want to say why you specifically want what you are applying for.
Best of luck to ya.