In decision making and psychology, decision fatigue refers to the deteriorating quality of decisions made by an individual, after a long session of decision making. 
Have you checked out Obama and Zuckerberg’s dress sense lately? Or maybe even what they wore 2 years ago? Chances are you couldn’t tell which year it was because they wear the same thing every day, Obama a black or grey suit and Zuckerberg a grey t-shirt, jeans and a hoodie. And they for it for the very reason of only making the best decisions.
Every decision you make from what you eat, what you will do tomorrow, what you will after work, it all takes energy to make. And if you were told you only had a certain amount of decisions to make every day before your judgment declines, would you really sweat the small stuff? As leaders, both Obama and Zuckerberg believe they should save their decisions for the bigger things.
If you think about it, you only have a certain amount of energy per day, and if you want to excel in something you really should only draw your attention to the things that matter. Besides the point, by creating a routine you are simplifying your life. Have less time to fret about the small things and more time for your goals and dreams.