Who said "I learned strength before I learned how to smile."?

This quote is attributed to Black Widow / Natasha Romanoff.

I learned strength before I learned how to smile. - Black Widow / Natasha Romanoff

"I learned strength before I learned how to smile."

Black Widow / Natasha Romanoff Strength

"I used to have nothing. Then I got this job, this team. It's all I have."

"Compromise where you can. Where you can't, don't."

"I'm always picking up after you boys."

"The world doesn't change without sacrifice."

"Strength comes from within."

"A woman should be proud of who she is."

"A strong woman can overcome anything."

"The only thing I'm good at is killing."