Sometimes, we find inspiration and sound advice in unexpected sources. Prompted by a friend, I recently read Jocko Willink’s “Way of the Warrior Kid III: Where There’s a Will … ” In this novel for adolescents, which is directed especially at boys, we meet Marc, a seventh-grader who’s having problems adjusting to Danny, a new kid in Marc’s circle of buddies. The trouble is that Danny, who’s always smiling and wants to be a friend, can best Marc in all sorts of athletic and academic contests. Marc’s Uncle Jake, a wise ex-Navy SEAL, takes his envious nephew under his wing, as he has in the two earlier novels, and adds to the Warrior Code that he has already taught Marc by pointing him in the direction of comradery, compassion, and understanding. Though Willink is unfamiliar to me, many of my readers have doubtless listened to his podcasts or read his …