The key to success in just about anything has a lot to do with finding who is doing something really, really well, and then lifting best practices from those people.

When it comes to productivity hacks, you have to set an especially high bar because, hey, we're all busy. So when I learned that Mark Cuban, Mark Zuckerberg, and Barack Obama all do one thing to maximize their productivity, it registered. After all, it's hard to imagine too many people that would have busier, more decision-packed days than these three.

The key words here are "decision-packed," because you also have decision-packed days, even if not on the same scale as these celebrity-type figures. Productivity breaks down when we spend too much time and energy making the myriad decisions we have to within a day. So the ex-leader of the free world, the CEO of one of the most important companies of all time, and an entrepreneur on overdrive all take the strain out of decision making with one trick.

They routinize as much as they can of their day.

Standardizing as many small decisions as possible, especially in the morning, is a great way to be more productive. You avoid "decision fatigue," a condition coined by social psychologist Roy Baumeister in which decisions get harder as the day goes and your energy wanes. Sound familiar?

So less decisions earlier in the day makes for more energy for bigger decisions later. Said Obama in an interview with Vanity Fair in 2012:

You'll see I wear only gray or blue. 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.

Mark Zuckerberg wears his trademark grey tee so much for the same reason, saying in a 2014 Q&A that he wanted to focus on building Facebook, and remarking, "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."

Mark Cuban sleeps in his gym clothes so he can get up and get to the gym without picking out what to workout in, and routinizes his breakfast, eating the same thing every morning, eight healthy(ish) oatmeal cookies.

These simple choices are so powerful for productivity. Here's why.

Baumeister's research likened the energy depletion of decision making to that of willpower. A series of experiments showed that when people were able to resist eating M&M's or fresh-baked chocolate chip cookies, they were later less able to resist other temptations. When respondents were forced to remain stoic and not cry during a sad movie, they gave up much more quickly on lab tasks requiring self-discipline like solving geometry puzzles. Baumeister proved that willpower was a form of energy that could be expended.

He then moved onto decision making to prove the same, this time by intercepting mall shoppers and asking them to solve a series of simple math problems. The ones who had been shopping far more, making more decisions on whether to buy this or that or to buy or not buy at all, gave up on the problems more quickly. Other experiments showed the same thing.

Set social psychology experiments aside, it just makes sense. When I've been making decisions all day and my daughter asks me in the evening do we want to see movie A or B, I'm tuckered out and ready to go see whatever, to just not make the decision.

As our desire and ability to decide wanes throughout the day, our productivity plummets. Indecision is the arch-enemy of productivity. It can paralyze organizations, create doubt, uncertainty, lack of focus, even resentment. It saps an organization's energy as multiple options linger and timelines and costs balloon.

So what seem like simple wardrobe and breakfast decisions, when routinized, is like weaponizing your day for productivity.