" Successful people know that hours, like capital, can be consciously allocated with the goal of creating riches—in the form of a changed world, a life’s work—over time. Indeed, successful people understand that work hours must be more carefully stewarded than capital because time is absolutely limited. You can earn more money, but the mightiest among us is granted no more than 168 hours per week, and it is physically impossible to work for all of them. "

― Laura Vanderkam , What the Most Successful People Do at Work: A Short Guide to Making Over Your Career