Nellisir
Hero
I think a raincoat would be a better choice of metaphore.
Impossible? no
Unlikely? yes
Well, nothing inspires you to make the world better like having a kid who has to live in it. That said, there's been research on happiness that shows people tend to have a baseline of happiness that they adhere to over time. If you're a happy person, you will tend to be a happy person. I am a happy person, and as I've gotten older, I've generally gotten better at being happy. My daughter is 90-95% happy, it's amazing. My wife is much more neutral, which can be difficult to deal with as I will literally be bouncing around and she just looks deadpan.
Downside, I have much larger deviations from the baseline. When she's happy, she's kinda happy, and when she's sad, she's kinda sad. When I'm happy I'm exuberant, and when I'm sad I'm miserable.