It's a characteristically chilly Melbourne winter morning and tech boss Tristan Sternson is starting the day by plunging into an ice bath. Just how icy? A bone-chilling 3 degrees Celsius — for 4 minutes. Next follows a "strict routine" of exercise, supplements, IV infusions and various treatments like saunas, cryotherapy, hyperbaric oxygen therapy … all in his quest to feel better and live longer.