Who said "I have learned that solitude can be a source of strength."?

This quote is attributed to Lady Sif.

I have learned that solitude can be a source of strength. - Lady Sif

"I have learned that solitude can be a source of strength."

Lady Sif Solitude

"I am a warrior of Asgard, and I will not falter in the face of darkness."

"Strength is not measured by the power of one's blade, but by the resolve of one's heart."

"A true friend stands beside you, not behind you."

"We are forged in battle, but refined through compassion."

"Sometimes being the best means being the loneliest."

"Solitude gives us time to reflect on what matters"

"I'm not good with people, never have been."

"I feel like I'm disappearing."