Researchers at the University of Kent in Canterbury, England, and other institutions reported on an experiment related to exercise fatigue and mindset (the article was published in Medicine & Science in Sports & Exercise). On one level, these findings indicate that “motivational self-talk improves endurance performance compared to not using it,” said Samuele Marcora, the director of exercise research at the University of Kent and senior author of the study. But a deeper reading of the data, he continued, buttresses the idea that physical exhaustion develops, to a considerable degree, in your head. “If the point in time at which people stop exercising was determined solely biologically,” he said, self-talk would have no effect. But it did. However, to be effective, self-talk likely must be consistent and systematic.