Getting a good education is very important to me not because I've been told so, but because I understand that being educated is important.
I believe this sentence is an example of a logical fellacy called "circular argument."
You are basically saying that getting a good education is very important because you know that it is important. I hope you find a way to fix that somehow...
Aristotle was the very first person in the West to provide the definition for "begging the question" fallacy, which is often considered similar to "circular argument," though he actually argued that while "begging the question" is a fallacy, "circular argument" isn't.
Aside from general education, I know I will value my college education since it will teach me real responsibilities and allow me to start my life.
I get what you mean, but you should rephrase "allow me to start my life" to "allow me to become independent of my parents" or something along that line.
I have had the opportunity to try many different sports, however sticking to water polo, wrestling, and discus in high school.
^Suggestion: "I had tried many different sports, but decided to focus on water polo, wrestling, and discus."
You cannot put a comma before "however", as it is an adverb, not a conjunction. If you want to keep "however", you should replace that comma with a semi-colon instead.
The reason I enjoy weightlifting so much is because it began to develop my physique, my strength, my athletic career, and the way many looked at me.
"The reason... because" is redundant. It should be "the reason... that."
as well as the bonus with the girls.
Again, I get what you are trying to say, but If I were you, I'd probably leave this part out. If you wanna keep it, then try to find another way to say "bonus with the girls."
Also, as in the case of this sentence,
The ancient Greeks have always been promoters of philosophy and natural sciences
you used present perfect tense when addressing events that took place in the past. Use simple past or past perfect.
I don't wanna sound too harsh, but there are many, many grammatical errors in this essay. It'd be a good idea to revise it with your English teacher... I hope this helps. :)