Who said "Sometimes the hardest battle is with yourself."?

This quote is attributed to Iron Fist.

Sometimes the hardest battle is with yourself. - Iron Fist

"Sometimes the hardest battle is with yourself."

Iron Fist Fear

"I am the living weapon. I am Iron Fist."

"I've trained my entire life for this moment."

"The chi flows through all living things."

"I need to protect the innocent."

"Face your fears with courage."

"You can't live your life in fear."

"Snakes. Why'd it have to be snakes?"

"Fear is just another obstacle to overcome."