We found parallel improvements in more than a dozen different outcomes that truly matter in our lives -- strength, endurance, flexibility, focus, reading ability, working memory, mood, stress, self-esteem, and happiness," he says. "Part of what distinguishes this work is finding such broad improvements across so many different domains, particularly given that the effect sizes were so large. Large effect sizes signify that the results were not only statistically significant but also indicative of substantial changes. Many of these effects were very large -- larger than you tend to find in studies that focus on changing only one thing.