The Start-up of You by Reid Hoffman and Ben Casnocha argues that a career should be approached like a start-up, requiring constant adaptation, networking, and intelligent risk-taking in today’s rapidly changing job market. The authors use the rise and fall of Detroit's auto industry as a cautionary tale about the dangers of failing to adapt to change. They emphasize the importance of building relationships, both strong alliances and diverse weak ties, as a key source of information and opportunity. The book also explores the concept of network intelligence, stressing the importance of knowing how to effectively access and synthesize information from your network to make informed career decisions.