You know that feeling at the end of a long day, the one where answering yet another question and making yet another decision feels like rolling a boulder up a hill.

There's a term for this. It's called "decision fatigue," and it became part of the vernacular in 2011 with the release of a study that showed judges in Israel were more likely to rule favorably at parole hearings at the beginning of each court session. Beyond the harrowing implications for prisoners, the study offers a global business takeaway: An executive's decision-making ability weakens with each successive decision he or she makes.

One way to keep your mind sharp: Keep mundane and inconsequential decisions to a minimum. "You may be surprised just how much small daily decisions impact the willpower you have for important choices," writes blogger and entrepreneur James Clear.

In the New York Times Magazine, science columnist John Tierney suggests that those who avoid decision fatigue turn small decisions into obligations. "Instead of deciding every morning whether or not to force themselves to exercise, they set up regular appointments to work out with a friend," he writes. "Instead of counting on willpower to remain robust all day, they conserve it so that it's available for emergencies and important decisions."

Clear advises putting off any small decisions that can't be turned into obligations until the end of the day.

"There will always be decisions that pop up each day that you can't plan for. That's fine. It's just part of life," Clear writes. "But for most of us, the decisions that drain us are the ones that we make over and over and over again. Wasting precious willpower these decisions--which could be automated or planned in advance--is one reason why many people feel so drained at the end of the day. For example, decisions like. . . . What am I going to wear to work? What should I eat for breakfast? Should I go to the dry cleaner before or after work? And so on.

"All of those examples above, can be decided in three minutes or less the night before, which means you won't be wasting your willpower on those choices the next day. Taking time to plan out, simplify, and design the repeated daily decisions will give you more mental space to make the important choices each day."