Who said "Strength is not measured in muscles, but in character."?

This quote is attributed to Underdog.

Strength is not measured in muscles, but in character. - Underdog

"Strength is not measured in muscles, but in character."

Underdog Strength

"There's no need to fear, Underdog is here!"

"When criminals in this city play, to steal the night and rob the day, they're out to make a dreadful mess, then Underdog is on the case."

"I'm just a pup who loves to help those in need."

"Even the smallest among us can make a big difference."

"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."