I can't say there are any quotes in particular that had a massive effect on me. There are plenty of people who have completely changing my perception with their works such as Emerson and Marcus Aurelius but no one quote has just made me have an epiphany. Still though, I have plenty of favorites. I'll list a few.
"What lies behind you and what lies in front of you, pales in comparison to what lies inside of you." - Emerson
"All life is an experiment. The more experiments you make the better." - Emerson
"Always do what you are afraid to do." - Emerson
“Give me health and a day, and I will make the pomp of emperors ridiculous.” - Emerson
"Once you make a decision, the universe conspires to make it happen." - Emerson (If you haven't noticed I love Emerson)
f a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away." - Thoreau
Pursue some path, however narrow and crooked, in which you can walk with love and reverence." - (I love Thoreau too. Transcendentalists are the best).
"When you arise in the morning, think of what a precious privilege it is to be alive - to breathe, to think, to enjoy, to love." - Marcus Aurelius
"Time is a sort of river of passing events, and strong is its current; no sooner is a thing brought to sight than it is swept by and another takes its place, and this too will be swept away." - Marcus Aurelius
"Out of suffering have emerged the strongest souls; the most massive characters are seared with scars." - Khalil Gibran
"March on. Do not tarry. To go forward is to move toward perfection. March on, and fear not the thorns, or the sharp stones on life's path." - Khalil Gibran
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens." - Khalil Gibran
Anyway, that's enough. I have so many quotes that I love but I've probably already gone overboard.