Growing up in New Zealand, where there are twenty times as many sheep as people, Sarah Robb O’Hagan wanted to be a veterinarian. When poor grades in science crushed that dream, she decided to see the world.

“Do what you love and you’ll never work a day in your life.” That’s one of those syrupy, motivational statements you see floating about the Internet. It’s often plastered on a photo of someone standing on a vista overlooking a mountain range, the ocean, a unicorn or all three if you happen to live in …