Control

What u say and wear, how u talk and show urself to other people, who u talk to and become friends w/, where u go and for what reasons. These things a person, YOU, can control.
Other things, on the other hand, cannot be controlled by u, no matter how much u want it to.
The way people react to different things, whether u'll be going to college w/ ur best friend, if u'll be moving to a different city, state, or country b/c of ur parents' job, whether or not u'll be living to see tomorrow. Things like these happen out of the blue. Sometimes u'll get a warning ahead of time and sometimes u wont.
It may seem sad/depressing to think of these things, but i learned from experience that it's inevitable and that it'll be a slap in the face if ur not ready.