Scott H Young has done a great job explaining how to achieve The 4 Hour Workday. I especially like how he advices not to add more work when you´ve completed your daily tasks early, and in so doing have precious time over to do things not work-related.

However, if you work at home, you have no excuse. Scheduling an eight-hour workday is wasting precious hours from your life. If you change how you evaluate your efforts, finishing eight hours of work in 3-4 hours is probable. You might even be able to increase your total output while reducing the amount you work.