This Truth About Willpower Can Help Make You Mentally StrongerBelieving you have everything you need is the first step to accomplishing your goals.

We've all had those days when your to-do list has taken on a life of its own and you think if you spend even a few more minutes at your desk, your head is going to explode. How do you find the wherewithal to keep going? But if you think willpower is something that can be depleted, that's actually a self-fulfilling prophecy, according to a recentstudy.

Researchers at the University of Illinois at Urbana-Champaign polled more than 1,100 Americans and 1,600 Europeans about how they thought about willpower. The participants were asked to rate how strongly they agreed or disagreed with statements such as, "After a strenuous mental activity, your energy is depleted, and you must rest to get it refueled again."

Related:6 Strategies to Maintain Your Willpower

As it turns out, the study found that the polled Americans said they believed they had less stamina for strenuous mental activity than the European participants did. The Americans were more likely to say that they required time to rest and recover after performing mentally stressful tasks, while the Europeans said they felt more able to begin the next activity immediately.

"When we view our willpower as limited, it's similar to a muscle that gets tired and needs rest. If we believe it is a finite resource, we act that way, feeling exhausted and needing breaks between demanding mental tasks, while people who view their willpower as a limitless resource get energized instead," explained lead study author Professor Christopher Napolitano.

Read more:How Your Daily Discipline Drives Success

Napolitano noted that simply changing your mindset is the key to building up a reserve of willpower. If you believe that you have it, you will. "Changing your beliefs about the nature of your self-control can have positive effects on development, leading to healthier behaviors and perceptions of others," he said.

Would you give this strategy a try? What do you to try to stretch yourself mentally? Let us know in the comments.