Celinne Da Costa quit her New York City advertising job and put her belongings in storage to set off on an unusual journey of exploration. She decided to couchsurf her way around the globe, only staying with people she met via social media. She's now writing a book about the journey that took her to 17 countries and the homes of 70 strangers. Mark chats with Celinne about the life-altering moment that made her leave her job, what she discovered on the road, and her practical tips for frequent and infrequent travelers.