Wow, there are several, but the first few that come to mind:
No day but today - from “Rent”. Cliche, yes… But I love it and it works for me. Always has, always will.
For God gave us not a spirit of fearfulness, but of power and love and discipline. - 2 Timothy 1:7. Speaks for itself, I think.
I may be changed by what happens to me, but I refuse to be reduced by it. - Maya Angelou. Pretty amazing lady, that Maya.
He that is without sin among you, let him be the first to cast a stone at her. - John 8:7. It isn’t a justification for “sin.” It isn’t a whiny “You’re not perfect either, so don’t judge me” excuse. It’s a reminder for me to not get on a high horse about anything—to remain humble—because in the overall scheme of things, I am no better than anyone else.