In a moment like this, it's a common thing to overreact about something as natural as somebody passing. We just have to appreciate life way more than we'll fear death, but this is understandably hard. The idea of all of Shane thoughts, ideas, love for his friends and relatives, emotional moments, his personality are gone forever along his material body is mind boggling. He just have changed from this organization to another.
This is the material world and to worry about material matters is a natural thing. That will include taking care of health, fitness, looks, but we are not those things or those things only.
We all have our expiration date, within a century to be optimistic, so it's up to us to correct our own track by the minute to make it worthy. As Hex mentioned, people easily forget about their own mortality. We came from somewhere, we are bound to somewhere. Only our present physical body came from "dust" and to "dust" shall turn back to.
Inevitable sadness lays on saying goodbye and missing a loved one, but we shall not allow room for desperation to settle in. Hundreds of kids won't have Shane's luck and success and will die way before puberty in terrible other ways. It's just the way things are on this dimension.
We shall not hope to be merely alive on this planet, but to make the best passage we can.
Don't worry. Shane still shines and so will we.