In Natalie Babbitt's Tuck Everlasting, both Winnie and Miles express wanting to make a difference in the world.
In the third chapter of the story, Winnie confides in a toad that she feels angry with her family and ready to run away from home. She is angry because, being an only child, her family members are constantly restricting her actions such as by telling her not to get her clothes dirty by sitting on the grass or telling her when to come inside. She feels so oppressed by her parents restricting her activities that she wants to run away from home even though she is not sure where she would go or what she would do. While telling the toad her troubles, she informs the toad that she wants to positively influence the world:
I'm not exactly sure what I'd do, you know, but something interesting--something that's all mine. Something that would make some kind of difference in the world. (Ch. 3)
Later, in chapter 17, Miles confides to Winnie that he has a similar ambition. The morning she wakes up in the Tucks' home, Miles takes her out fishing in the row boat. While in the boat, Winnie asks him what he will do with all the time he has to live. Miles replies, "Someday, ... I'll find a way to do something important," and Winnie is immediately struck by the similarity of their ambitions. He further says he has no idea what he wants to do but knows he believes people should do "something useful" with their lives. He imagines he might fulfill his ambition by making some important discovery in the future.