Limited Willpower Can Affect Your Workout

Study Shows Self-Control Comes in Limited Doses

Reviewed by Louise Chang, MD on September 25, 2009

Sept. 25, 2009 -- You want to exercise. You know you should be exercising more. But even though you up wake every morning committed to hitting the gym or taking a long walk after work, your resolve is gone by the end of a long day.

Sound familiar?

For some lucky people, exercise is second nature. For the rest of us it takes willpower.

Now new research suggests that one big reason people fail to follow through on their exercise plans is that they have used up their willpower on other tasks.

The study examined the theory that people have limited stores of self-control, or willpower, in any given day.

Just like the money in your wallet, the theory goes, willpower is a finite resource that can't be used on one thing if it is already spent on another.

"When you use self-control for other things -- like meeting a deadline at work or resisting the temptation to eat a doughnut -- you deplete your pool of self-control," exercise scientist Kathleen Martin Ginis, PhD, of McMaster University tells WebMD. "We wanted to see how that impacted exercise."

Ginis and colleague Steven R. Bray, PhD, designed a laboratory experiment to do just that and recruited 61 university students who were not regular exercisers to take part.

The students were initially asked to work out on lab-based exercise machines. Half the participants were then asked to perform a task, known as the Stroop test, designed to deplete their willpower stores.

The test involved showing the students the words for colors printed in a different color. For example, the word red might be printed in green ink and so on.

The students were told to say the color they saw, and resist the temptation to say the color they were reading.

"It sounds pretty innocuous, but it definitely takes self-control to ignore the written word," Martin Ginis says.

The students were then subjected to a second round of exercise, and, as the researchers had suspected, those whose willpower had been challenged did not work out with the same intensity as those who had not taken the test.

The willpower-challenged students also worked out less over the next eight weeks.

The study was published this week in the journal Psychology and Health.

No Excuse to Stay on the Couch

So is there little hope for people who need willpower to exercise, but never seem to have enough?

Not at all, Martin Ginis says.

"The good news is self-control is like a muscle, and the more it is flexed the bigger it gets," she says. "The more you challenge yourself by doing things like resisting that chocolate cake or resisting the urge to hit the snooze button in the morning the more you build self-control."

Boston psychologist Eric Endlich, PhD, who specializes in motivating patients to diet and exercise, tells WebMD that having a plan for exercise can make all the difference.

Strategies recommended by Endlich and Martin Ginis include:

  • Schedule exercise. Plan your exercise, including trips to the gym and the classes you want to take, ahead of time and have everything ready to go to avoid that 20-minute search for your running shoes. "If you've planned what you are doing and have everything ready, you avoid the big debate with yourself about whether you will do it or not," Endlich says.
  • Get a trainer or an exercise buddy. Being accountable to someone else is a great motivator.
  • Get it over with. If you know you can't make yourself exercise after an exhausting day, do it first thing in the morning.
  • Get in a good mood. Studies suggest that people can muster more self-control when they are in a good mood, Martin Ginis says. So listening to music that makes you happy or watching something funny online could be just the motivator you need.

Show Sources


Martin Ginis, K.A. Psychology and Health, Sept. 24, 2009.

Kathleen A. Martin Ginis, PhD, associate professor of kinesiology, McMaster University, Hamilton, Ontario, Canada.

Eric Endlich, PhD, psychologist, Boston.

News release, McMaster University.

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