https://www.scientificamerican.com/article/being-a-couch-potato-may-change-your-personality1/

A sedentary lifestyle has long been linked to poor health, and a growing body of evidence suggests it may also affect personality. Previous research found associations between a lack of exercise and declines in character traits such as conscientiousness, measured four to 10 years after initial surveys. Now the largest analysis of its kind to date has used longer follow-up periods to confirm these links and show they persist up to nearly two decades.

A team led by psychologist Yannick Stephan of the University of Montpellier in France reached this conclusion after combining data from two large, survey-based studies. The Wisconsin Longitudinal Study (WLS) followed people who had graduated from that state's high schools in 1957, as well as some of their siblings. The Midlife in the United States (MIDUS) study recruited people from across the country. Participants in both had completed personality questionnaires when first recruited in the 1990s and answered questions about their exercise habits and health.