what's the major things that make you change?

my english teacher asked me, "what's the major things that make you change?" . hmm.and i think in a few minutes.my major things that make me change i think when i'm in the college. i've been looking a different life of the student in the college. as we know, campus provide their student a freedom, and we must be feel very free than when we were in the senior high. When we were in the senior high we must very discipline and the rules is very strict. So, when we're in the college we will feel the freedom in the campus because the rules is not really strict.
but, from that freedom, we must be careful.i think i must have a principle . i think that i must control my self to make me far from the negative things.if we can't control our self it will damage our self
for example, i've been looking many girls and boys smoking. i don't really like if someone smoking esp. the girls, i don't know why but it's unsightly and there's no an advantages of smoking. another example is many students were skip the class.Sometimes, i was thought of it, but i didn't do that because i didn't want to do it anymore as i did when i'm in the high school. i prefer to focus on my study than i must do something which is useless because i want to be a graduate as soon as possible. beside that, my father has been working in my college and that's the primary reason why i don't want to skip the class, haha .
So, since i'm in the college, it made ​​me become more mature and I am more able to choose which one is good or not to do. I prefer to think repeatedly of doing something. didn't do recklessly things anymore :)