Well, that depends entirely on your character's personality. A lot of kid hero stories work because the hero has had this basically forced upon them. Things like Ben10 he has this power and he needs to do something about it., everyone else important knows and help him with this, and there's heroing along the way.
Really, when it comes to heroing, you have 2 basic options: either because the hero is personally involved and so it doing it for mostly selfish reasons, or you have to go out of your way to show them as stupidly heroic. In the first category you have things like they'll die if they don't, someone they love will die if they don't, someone's been kidnapped that's important to them ect. In the second category, you have idiots mostly, but also some much more interesting things like they don't value their own life, they measure their own worth on how they help others, it's all they've been raised to do, it's their duty ect.