Timothy Ferriss is an American entrepreneur, investor, author, podcaster, and lifestyle guru. He is known for his 4-Hour self-help book series—including The 4-Hour Work Week, The 4-Hour Body, and The 4-Hour Chef—that focused on lifestyle optimizations, but he has since reconsidered this approach.

The 4-Hour Workweek: Escape 9–5, Live Anywhere, and Join the New Rich (2007) is a self-help book by Timothy Ferriss, an American writer, educational activist, and entrepreneur. It deals with what Ferriss refers to as "lifestyle design", and repudiates the traditional "deferred" life plan in which people work grueling hours and take few vacations for decades and save money in order to relax after retirement. The book spent four years on The New York Times Best Seller List, was translated into 40 languages, and sold around 2.1 million copies.