Being an entrepreneur means making hundreds decisions, most of which -- especially during the startup phase -- feel like they have the power to make or break your business.

Unfortunately, we all have a finite amount of mental energy. Sure, exercise can improve memory and cognitive skills. It can lower symptoms of fatigue by as much as 65 percent. It can help you better manage stress.

Even so: Make enough decisions in one day and decision fatigue naturally sets in. The more decisions you have to make, the harder each one is on your brain. 

Which can lead you to stop making considered decisions and start looking for shortcuts. Not because you don't care, but because you run out of the mental energy required to make wise choices.

According to Tim Ferriss, that's why Southwest Airlines founder Herb Kelleher applied a simple framework to every issue, problem, or question: 

Will this help Southwest be the lowest-cost provider? 

Filtering every issue through that lens made things simple for Herb.

And it can for you too. Just apply the same framework to the decisions you make, whether personal or professional. "Will this help me reach my goal?" 

Take me. I'm sometimes asked to do what seem like cool things. Serve on startup advisory boards. Appear on podcasts. Write forewords for other people's books.

I'm always flattered. And, since temptation usually follows flattery, I'm always tempted.  

But then I take a step back and ask myself one question: "Will this help me become a more successful writer or speaker?"

The answer is almost always no. Unless Adam Grant or Joe Rogan asks me to appear on their podcasts, or Malcolm Gladwell asks me to write the foreword for a new book (none of which is ever likely to happen, which is basically the point), my time is better spent delivering a virtual keynote or writing my own stuff. 

Try it. Take a step back and reflect on what makes the biggest difference in your business. Maybe, as it is for Southwest Airlines, the one thing is price. Or quality. Or service. Or how you lead and develop your people.

Even if the issue seems, at first glance, extremely complicated.

For example, when I was a supervisor in a book manufacturing plant, an employee noticed a quality problem late in a production run on a job that needed to ship that day to meet the delivery date. Re-running the job would result in a major spoilage. The impact on production schedules would mean other jobs would ship late as well. (Plus, pulling the job would make me look bad.) An endless stream of cost/benefit scenarios ran through my head as I struggled to decide what to do. 

Then an employee from another line walked over. He picked up one of the books and immediately spotted the problem. "Aw, man," he said, "that sucks," tossing the book onto a "kill" pallet.

He had asked himself one question: "Does this meet customer quality standards?"

Since the answer was no, to him (and eventually to me) the decision was obvious.

Keep in mind you can also apply the "one question" framework to personal goals. Say you don't want to just exercise. Say you want to be fit. Imagine you're dining out and the waiter asks if you want dessert. 

"Would a fit person have dessert?"

Probably not. 

Of course, if you had run 14 miles that day and burned a ton of calories, and having dessert today would fit within your plan, then the answer might be yes.  

Either way, you know the answer -- without thinking. Which means decision fatigue doesn't factor in since you actually made your decision before the choice was ever presented to you.

What do you want to achieve? Whom do you want to become? Place yourself there. Say "I run a $20 million business." Or "I am a servant leader." Or "Our business makes a real difference in the lives of our customers."

Whatever your goal, every time you need to make a decision, ask yourself the one question that reflects your goal.

"Will this help me build a $20 million business?" "Will this help me better serve the people I lead?" "Will this make a real difference in the lives of our customers?"

Do that, and almost every decision you need to make will be easy.

And you'll be much more likely to achieve the goal you set, because your actions will consistently reflect your ultimate intention.