With a new semester comes an opportunity to plan a workout regimen that fits into your new schedule and fulfills your personal goals for improved health and fitness. When looking forward to the benefits you hope to gain through regular exercise—better overall health, mood and concentration—it is essential to recognize the important role willpower plays in decision-making.

The Science Daily article, “Tough Day at Work? You Won’t Feel Like Exercising,” examines a study in Psychology and Health that concluded that one has a limited supply of willpower, meaning after it has been expended in one difficult activity, it will be unable to perform to the same standard in the second. This pertains to both cognitive and emotional stress, according to Associate Professor Kathleen Martin Ginis at McMaster University, and this may surprise some. Often we associate willpower with acts of self-regulation, challenge or patience, but it is used just as frequently in concentration, handling emotional distress and activities that require heightened brain activity.

In the study performed by Martin Ginis and colleague Steven Bray, participants were asked to complete a Stroop test—a challenging cognitive test involving words and colors—then track their exercise habits. The group that had expended their willpower in the cognitive test was less inclined to complete their workout regimen for the remainder of the study.

Cognizance Magazine published an article, “The Limits of Willpower,” describing a similar experiment performed on college students that expended their willpower in a simple eating exercise. Students entered a room filled with the aroma of freshly baked chocolate chip cookies and were divided into two groups at the table. One group was told to eat two cookies while the other group was told to eat two radishes while the researchers waited outside the room to increase their use of willpower with the opportunity to “cheat.” After the first use of willpower, both groups were given impossible puzzles to solve, and the disparity between uses of willpower was measurable. Those in the cookie tasting group spent 11 minutes longer on the task than the radish tasting group, as their willpower had already been exhausted in the previous exercise.

Knowing the limits to willpower is especially important to students who seek to improve their health through exercise. It affirms a familiar reality often experienced by those who are disappointed that they don’t have the drive to work out after a long day of class. If one’s classes have been particularly trying, the willpower to exercise will be more difficult to summon, but this should not be an excuse to forego exercise all together.

This finding also provides an incentive for students to wake up early and exercise before confronting the stresses of a busy schedule. In fact, exercising before attending class may improve one’s ability to concentrate, according to the article “Does Exercise Improve Concentration?” by Matthew Lee. In the article Lee reports the findings of a study in 2007 that found even 15 minutes of exercise improved the concentration, memory and behavior of elementary students, and other studies have shown physical activity to benefit concentration and improve academic performance.

If waking up early is not an option, however, don’t despair; seeking to improve one’s willpower has proven both possible and effective. Efforts to improve willpower are likely to have positive and noticeable results if the effort becomes habitual. Recent findings by The Miriam Hospital’s Weight Control and Diabetes Research Center have shown that practicing self-control through diet and exercise regimens increase one’s capacity to exercise increased willpower.

“Willpower is like a muscle: it needs to be challenged to build itself,” Martin Ginis said.