My oldest son runs ultra-marathons from time to time, whereas for me, an ultra-marathon is staying awake from 3 a.m. to 10 p.m. with just one nap. At any rate, this Christmas he gifted me with a copy of Jesse Itzler’s “Living with a SEAL: 31 Days Training with the Toughest Man on the Planet” (Center Street, 2016, 288 pages).