Deadline by Crutcher

The summer before senior year, Ben Wolf is diagnosed with terminal leukemia. Because he's 18 and wants a "normal" life for as long as possible, Ben decides not to tell anyone. Instead, he does everything he was too afraid to do - go out for football, pursue the volleyball player who's a foot taller than him, challenge his teacher, and befriend the reclusive McCoy who has a secret of his own. In fact, just about everyone has something they've kept hidden, bringing up the question of whether secrets ultimately help or hurt others. Some of the book is intense and there is frank conversation about sexual abuse, but it doesn't get too heavy. A worthy read for anyone wondering what life is all about.