“You can't really know what you are made of until you are tested.”
“You never know what's in a person's heart until they're tested, do you?”
“You can't know what you need to know until it's up for you to know it.”
“You can't really get to know a person until you get in their shoes and walk around in them.”
“Until you try, you don't know what you can't do.”
“You never know what you really believe until you have to defend it.”