"It's never too late for the adventure of a lifetime. In all the ways that matter, Mark is a normal kid. He's got a dog named Beau and a best friend, Jessie. He likes to take photos and write haiku poems in his notebook. He dreams of climbing a mountain one day. But in one important way, Mark is not like other kids at all. Mark is sick. The kind of sick that means hospitals. And treatments. The kind of sick some people never get better from. So Mark...