They don't always fit the situation, and I'm not always successful but memorizing words I love and wielding them as a mantra or meditation that I say over and over again in my head can help me focus and change directions. I suppose some would consider it sacrilegious that I'm using the word mantra in this fashion, but that's how I see it and that's what they are for me.
It's probably obvious, but I turn to the Bene Gesserit Litany Against Fear most often:
"I must not fear.
Fear is the mind-killer.
Fear is the little-death that brings total obliteration.
I will face my fear.
I will permit it to pass over me and through me.
And when it has gone past I will turn the inner eye to see its path.
Where the fear has gone there will be nothing......Only I will remain."
Frank Herbert's words from Dune ring with truth and give me a boost of bravery when I need it - which is often.
Another one I repeat is the oath for the Night's Watch from A Song of Ice and Fire. I memorized it once, and it's stuck with me and it's there at the tip of my fingertips when I need to pull together and focus.
"Night gathers, and now my watch begins. It shall not end until my death. I shall take no wife, hold no lands, father no children. I shall wear no crowns and win no glory. I shall live and die at my post. I am the sword in the darkness. I am the watcher on the walls. I am the fire that burns against the cold, the light that brings the dawn, the horn that wakes the sleepers, the shield that guards the realms of men. I pledge my life and honor to the Night's Watch, for this night and all the nights to come."
I'm not planning to take the black any time ever, but something about the cadence and language calms me.
I also turns to wise words from J.R.R. Tolkien. More than a couple of poems in the Lord of the Rings trilogy can brighten my day but this is the only one I have committed to memory:
All that is gold does not glitter,Not all those who wander are lost;
The old that is strong does not wither,
Deep roots are not reached by the frost.
From the ashes a fire shall be woken,
A light from the shadows shall spring;
Renewed shall be blade that was broken,
The crownless again shall be king.
The first verse especially is a helpful reminder when I'm feeling like I've lost my way or that I'm not accomplishing all that I should be.
Written out, it seems silly that these bits from fiction are what I turn towards when I'm struggling but they help me get through those rough moments and you've got to celebrate whatever works.