First, "Marines don't die. They just regroup in hell to kick satans ass! - Unknown
Second, "All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dreams with open eyes, to make it possible. This I did."
— T.E Lawrence "Lawrence of Arabia"
Sure, I could always quote some famous person, (who's very likely insane, like Lovecraft, Poe, or Nietzsche) but I think you all need a little inspiration from Thorse in your life.
"No matter how many times I come here, it still gets to me. You look at a name, and you have to look at a reflection of yourself. You are among the fallen." - Special Agent Leeroy Jethro Gibbs
"To the end." - Jak
"Total security has never been available to anyone. To expect it is unrealistic, to imagine that it can exist is an invite to disaster." - Edward Teller
And here is a compilation of my absolute favorites