The big mistake we make is that when kids ask us "so who should be an engineer?" we say "Well, you should be really good at math & science."
I was not "really good" at math and science. I enjoyed science. I was slow on my multiplication tables. Algebra didn't even really click with me, until I was like 17. I was not in any advanced math classes, I was just average.
I was good at some math, like geometry and proofs. But I think it was just by chance. It's a sad thing in our country that we think of math as this one big thing, when it's such a diverse field. Saying you're bad at math is like saying you don't like pie. Really, you don't like any pie? Apple pie, pumpkin pie, chocolate pie, lemon meringue? You really hate every kind of pie?
But despite not being a math wiz, I've done well as an engineer. I'm enthusiastic, I like figuring out where to start, I like explaining things to people, I'm good at organizing things, I'm motivated by improving the world. All of this is important.
Saying that you should be an engineer if you're good at math is like saying that you should be an artist if you like drawing lines, or you should be an accountant if you like balancing your checkbook. There are plenty of people who like that stuff, there are plenty who don't. It's especially hard when you say those things to a 12-year-old, because their view of the world of math is so limited, you risk having them associate "engineering" with those multiplication tables. It's not that at all.
Of course you have to be smart enough to know what 6x4 is, but I think every well-paying field requires that level of intelligence. What separates engineering is the problem solving, the environment, who you work with, the projects you work on... that's what makes it the career for you.