India, Oct. 18 -- A 34-year-old woman quit her Wall Street legal career to spend a year living out of her car and exploring the American West. Her best friend, Erin, was stunned by the decision, asking, "You're joking, right?" The unconventional move left her worried about losing their 16-year friendship.

The woman and Erin met during their first year at college, where they were scholarship athletes on a competitive Division I track team. After graduating, both pursued demanding corporate careers in East Coast cities, building their friendship around shared experiences, professional ambitions and similar lifestyles.

"We'd only ever let ourselves be so vulnerable with each other," she recalled, explaining how she had shared her frustrati...