"A boy who wont stand up for himself becomes a man who can't stand up to anything"

In my personal thoughts I think the quote means that if you don't take up for or stand up for yourself in a early age, when you grow up you will be the same and standing up for yourself is an important part of being a man. Also in the book "The Kite Runner" Baba said this to Rahim Khan and Rahim Khan said it to Amir.