Facebook co-founder and CEO Mark Zuckerberg doesn't wear his signature gray tee simply because he loves the style. Nor does self-made billionaire John Paul DeJoria have a particular affinity for his all-black clothes.
It turns out there's a scientific reason the billionaires routinely wear the same thing. By sticking to a kind of uniform, they're avoiding a phenomenon known as decision fatigue, which describes the way choices become harder and harder as a day goes on and your finite store of energy gets depleted.
As Zuckerberg said during a public Q&A session in 2014, "I really want to clear my life to make it so that I have to make as few decisions as possible about anything except how to best serve this community. ... I feel like I'm not doing my job if I spend any of my energy on things that are silly or frivolous about my life."
John Paul DeJoria, who went from homeless to building two billion-dollar companies, actually started wearing all black to keep his dry cleaning bill lower, he tells Farnoosh Torabi on CNBC's show, "Follow the Leader."
The self-made billionaire no longer has to worry about cutting laundry costs, but the wardrobe habit he formed offers more than a financial benefit. As Torabi writes, "Wearing repeat outfits means he can spend less time and thought worrying about what to wear. Instead he can apply those resources to more important things like family and business."
And then there's President Barack Obama and his suits.
"You'll see I wear only gray or blue suits," he told Vanity Fair in 2012. "I'm trying to pare down decisions. I don't want to make decisions about what I'm eating or wearing. Because I have too many other decisions to make.
"You need to focus your decision-making energy. You need to routinize yourself. You can't be going through the day distracted by trivia."
Science suggests that these successful men are onto something. And if it works for them, it could work for you.