Today is the feast of St Agnes. She numbers among one of those few teen saints. We heard this morning from Ambrose of Milan on the subject (he is pretty much the earliest source on her).
He talks of her valour in the face of persecution and execution, her determination to remain true to her faith despite the very real threat of death for doing so.
Just like Jeremiah and Timothy from the Bible, Agnes shows that there's no such thing as being too young to witness to your faith.