14 Factors That Affect the Decisions You Make

President Obama only wears blue or gray suits.

As he told Vanity Fair, it’s a way of managing his willpower.

“I’m trying to pare down decisions,” he says. “I don’t want to make decisions about what I’m eating or wearing. Because I have too many other decisions to make.”

Obama’s focus on routine is backed up by research. Social psychologist Roy Baumeister has found that willpower is like a muscle — it can be strengthened or fatigued with use.

It’s a crucial insight, given that a 2011 study of 1 million people around the world found that people think that self-control is their biggest weakness or character failure.

As Baumeister details in his book Willpower: The Greatest Human Strength and a New York Times Magazine cover story, willpower and decision-making are interconnected. The house you grew up in, the number of decisions you made today, and what your friends are doing, all affect your decisions in weird ways. Here’s a look at how.

Make your most important decisions in the morning, before you experience ‘ego depletion’

“Freud speculated that the self, or ego, depended on mental activities involving the transfer of energy,” the New York Times reports. “[His] experiments demonstrated that there is a finite store of mental energy for exerting self-control.”

As the day wears on, your energy reserves are further depleted.

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Your brain needs glucose in order to make good decisions

“Even the wisest people won’t make good choices when they’re not rested and their glucose is low,” Baumeister tells the Times. “That’s why the truly wise don’t restructure the company at 4 p.m. They don’t make major commitments during the cocktail hour. And if a decision must be made late in the day, they know not to do it on an empty stomach.”

Grocery retailers discovered this decades ago.

Researchers found that, “just when shoppers are depleted after all their decisions in the aisles — with their willpower reduced, they’re more likely to yield to any kind of temptation, but they’re especially vulnerable to candy and soda and anything else offering a quick hit of sugar.”

Our finite supply of ‘decision-making power’ means that making a series of decisions can be exhausting

Which would explain why shopping is so tiring.

Researchers found that shoppers who “had already made the most decisions in the stores gave up the quickest” on a math test.

Once you’re mentally depleted, you’re more likely to make bad decisions

“To compromise is a complex human ability and therefore one of the first to decline when willpower is depleted,” reports the Times.

At the end of the day, when we’re more physically and mentally fatigued, we’re more likely to skip the gym after work or drink more during happy hour.

Developing routines helps you eliminate stress and conserve energy for important decisions

“The most successful people, Baumeister and his colleagues have found, don’t use their willpower as a last-ditch defense to stop themselves from disaster,” the Times reports.

“Rather, they conserve willpower by developing effective habits and routines in school and at work so that they reduce the amount of stress in their lives. They use their self-control not to get through crises but to avoid them. They give themselves enough time to finish a project; they take the car to the shop before it breaks down.”

If you want more willpower, get better sleep

Studies equate sleep deprivation — getting less than six hours a night — with being drunk. As Stanford health psychologist Kelly McGonigal says, sleep deprivation messes with the prefrontal cortex, a region of the brain associated with decision-making.

When you’re sleep deprived, “the prefrontal cortex is especially hard hit and it loses control over the regions of the brain that create cravings and the stress response,” she says. “Unchecked, the brain overreacts to ordinary, everyday stress and temptation.”

Your unconscious plays a key role in helping you make good decisions

President Obama’s decision to “sleep on it” —it being whether or not to raid Osama Bin Laden’s compound — aligns with psychologists’ recommendations for complex decision making.

“Because your conscious attention is limited, you should enlist the help of your unconscious,” according to the Harvard Business Review.

Even if you don’t have the option to delay your decision for long, engaging in another activity will take your mind off your dilemma, and allow your unconscious to surface.

Your decisions are shaped by your friends and family

Breakthroughs in network science — the study of social groups — have revealed how many things we tend to think of as being individual, like whether you get fat or stop smoking, are actually collective.

As James Fowler of the University of California, San Diego, and Nick Christakis of Harvard Medical School have found, our behaviors are contagious. If your best friend becomes obese, you have a 57% greater chance of growing obese too. If a close colleague quits smoking, you have a 34% greater change of quitting smoking, too.

Sometimes, it’s best to run your ideas by others

Network science has insights into productivity, too.

When researchers tracked the successes of individuals at an aerospace company, including patents and products those individuals brought to market, they found that who a given engineer knew was tremendously important.

After experience, the relationships that an individual had were the greatest predictor of success. The people who had relationships up and down hierarchy and across departments were the most likely to succeed by the company’s metrics.

Why? Because when you have quality relationships with people, you can combine ideas, gather feedback, and earn buy-in for your projects — another reason that generous people succeed.

It can be valuable to cave in and say ‘yes’ to the ‘wrong choices’ once in a while

Occasionally giving in to your desires can reinvigorate you, so you don’t feel completely deprived all the time, according to the Times. It helps you stay on track for the long-term.

There’s a reason why people celebrate Mardi Gras before the Lenten season.

If you make an obligation to someone, the decision gets easier

Are there decisions you don’t have to make right now, or you can have someone else make for you?

“Instead of deciding every morning whether or not to force themselves to exercise, [smart people] set up regular appointments to work out with a friend,” reports the Times.

If you prepare for your moments of weakness, you’ll be better able to make good decisions

“Good decision making is not a trait of the person, in the sense that it’s always there,” Baumeister says. “It’s a state that fluctuates.” The Times reports:

His studies show that people with the best self-control are the ones who structure their lives so as to conserve willpower. They don’t schedule endless back-to-back meetings. They avoid temptations like all-you-can-eat buffets, and they establish habits that eliminate the mental effort of making choices. … Instead of counting on willpower to remain robust all day, they conserve it so that it’s available for emergencies and important decisions.

“The best decision makers are the ones,” he says, “who know when not to trust themselves.”

If you can exercise your willpower, studies suggest you’re more likely to succeed

In the famous 1972 Stanford marshmallow experiment, school children were asked to sit at a table with a marshmallow in front of them and not eat it — for an excruciating 15 minutes. They got a sweet pay off if they made it: a second marshmallow.

As has been widely reported, the students that could wait for the second treat had higher SAT scores and lower levels of substance abuse than their more impulsive friends.

But the waiting game might not be the whole story…

But sometimes what looks like weak willpower could be quality decision making

If it looks like the opportunity to act might disappear, it can be better not to wait.

In 2012, University of Rochester researcher Celeste Kidd published a study that challenged that marshmallow experiment. When she was younger, Kidd spent time working for homeless shelters — she remembers wondering how growing up in such an unstable situation would affect decision-making.

Those kids, she thought, would eat the marshmallow right away.

But not because they didn’t have enough willpower. Rather, they grew up in situations where you they couldn’t trust adults to follow through on their promises.

“Our results definitely temper the popular perception that marshmallow-like tasks are very powerful diagnostics for self-control capacity,” Kidd said. “Delaying gratification is only the rational choice if the child believes a second marshmallow is likely to be delivered after a reasonably short delay.”

In Kidd’s study, children were primed to think that researchers were reliable or unreliable. In one part of the study, the experimenter gave the kids a piece of paper and crayons, telling the child to use those art supplies or wait for better ones. Then came the twist: for one group of students, the experimenter brought back markers and crayons; for the other, the experimenter came back and apologized, saying there weren’t any nicer art supplies.

Then came the marshmallow test. The nine of the 14 kids from the “reliable” set were able to wait 15 minutes for the second marshmallow, but just one of the 14 waited it out.

The lesson: what looks like willpower might also be trust.

This article originally appeared on Business Insider