I heard this recently in a briefing exercise. I think it is one of the best quotes on mindset I have ever heard.
"Everyone says, Failure is not an option. It's quite the contrary, failure is ALWAYS and ever present option. There is always that chance of failure. FEAR is never an option. If you fear to attempt, then you will never succeed...or fail. Do not let fear paralyze you. Failure is always an option, Fear is not." - Anonymous source
"Of every one hundred men, Ten shouldn't even be there, Eighty are nothing but targets, Nine are real fighters...We are lucky to have them...They make the battle. Ah, but the One, One of them is a Warrior...and He will bring the others back." -Hericletus