Motivation takes many forms; the only real kind being from already motivated individuals themselves, and not anti-social drudge from the internet. So why am I talking about it? Because I have indeed, experienced it. Actually, not really. I'm more of a self motivator, by way of "shit if I don't get this done my mom's gonna be all over me." But I've seen plenty in anime.
Behind every wimpy little guy is a bad-ass motivating him.
|Pictured: Wimp (top); Badass (bottom).|
So how do you make them understand? You beat it into them.
Kamina, Gendo, or any other manly man that had to stand watch over a little sissy boy that would somehow eventually take charge and save the world, they smack sense into people.
Of course, in real life they bring up things like "child abuse" and "child services" but none of that shit matters in post-apocalyptic settings. Children are of course the only way to save the world, after all.