A prospective cohort study recently published in the Mayo Clinic Proceedings found that a self-reported brisk walking pace was associated with longer life expectancy across all weight categories—from underweight to obese, compared with those who reported being slow walkers. The cohort included nearly 475,000 middle-aged British men and women followed over about seven years. The group associated with the shortest life expectancy was slow walkers with a body mass index (BMI) under 20. This group may include underweight individuals who are ill or frail. Low BMI can be associated with sarcopenia (loss of muscle mass and strength in older adults) and suboptimal nutritional status. This study adds to other data associating indices of physical fitness with risk of death from cardiovascular disease and other causes, reinforcing the importance of staying active as a major component of maintaining health with advancing years.