"Decide in your heart of hearts what really excites and challenges you, and start moving your life in that direction. Every decision you make, from what you eat to what you do with your time tonight, turns you into who you are tomorrow, and the day after that. Look at who you want to be, and start sculpting yourself into that person. You may not get exactly where you thought you'd be, but you will be doing things that suit you in a profession you believe in. Don't let life randomly kick you into the adult you don't want to become."
Chris Hadfield, Canadian astronaut, found on zenpencils.com
A second one from the webcomic "Order of the Stick":
"You're not a type! You're a person, a person who does stuff! If you want to be different, do different stuff! Look at me. I used to be a town guard, and then I decided I wanted to be a cleric. Did everyone I know tell me, "Oh, I don't really think you're the type to be a cleric"? Yes! Did I listen to them? No! If anyone tells you that you can't be better if you want to be, you punch them in their stupid judgy face! And you know what the best part is? When you make a change, everyone who meets you from that point on? Only knows the new version of you. And that's nice."
And a last one:
"Any society that would give up a little liberty to gain a little security will deserve neither and lose both."
Chris Hadfield, Canadian astronaut, found on zenpencils.com
A second one from the webcomic "Order of the Stick":
"You're not a type! You're a person, a person who does stuff! If you want to be different, do different stuff! Look at me. I used to be a town guard, and then I decided I wanted to be a cleric. Did everyone I know tell me, "Oh, I don't really think you're the type to be a cleric"? Yes! Did I listen to them? No! If anyone tells you that you can't be better if you want to be, you punch them in their stupid judgy face! And you know what the best part is? When you make a change, everyone who meets you from that point on? Only knows the new version of you. And that's nice."
And a last one:
"Any society that would give up a little liberty to gain a little security will deserve neither and lose both."
Benjamin Franklin, found in Civilization IV