I saw this challenge and I couldn't help my self, when I hear about strong women Yuna always comes to my mind. I think she has one of the strongest wills out of everyone I've seen in video games.
She is just a teenager willing to end her life, for 10 years worth of peace for the world she lives in. She would die not only for her friends and family, but for everyone around her that she has never met. She truly believed in Yevon and when she found out everything she believed in was a lie, her will didn't break she contiuned her journey to save the people of spira. Everyone turned their backs on her, called her a traitor she still fought on with no regrets to end her life for those who now hated her. Mentally and emotionly she as the will stronger than steel.

Links:
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http://de.finalfantasy.wikia.com/wiki/Benutzer:Riosaix/Walkthrough:Final_Fantasy_X/Part_4

The link for the picture of her isn't great, I can't find a good one to get it. But it's an official picture that you can easily find of her. O.o Let me know if you need a better link haha