IF you can keep your head when all about you
Are losing theirs and blaming it on you,
If you can trust yourself when all men doubt you,
But make allowance for their doubting too;
If you can wait and not be tired by waiting,
Or being lied about, don't deal in lies,
Or being hated, don't give way to hating,
And yet don't look too good, nor talk too wise:
If you can dream - and not make dreams your master;
If you can make one heap of all your winnings
If you can talk with crowds and keep your virtue,
One of the greats right there. Honestly I was never much of a poetry buff until more recently but it's certainly an effective tradecraft.
Here's one I consider to be extremely potent and meaningful:
"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."
More on it: