Below is a one of those "scientists' stories" videos by the American Chemical Society. They have a bunch more up which I recommend (here). I'm struck by the detail in her "how I got into science" story about her high school history teacher directly telling her 1) that she was going to be a scientist, and 2) how to get started. It seems remarkable that a student could show both an interest in and aptitude for science, for a while, but need to be told directly: "You could be a scientist." I have heard many stories like this from people who end up in science careers. Often around high school or college, some mentor-type person will say "You seem interested in this science stuff. You know you could be a scientist, right? Here's how to get started.".
You too could have a significant effect on a future-scientist by saying something that simple. See, mentoring is easy!