Sitting for more than three hours a day can cut two years off a person's life expectancy.

The statement is true because extensive sitting for more than three hours a day has been linked to various negative health consequences that can ultimately reduce a person's life expectancy. Prolonged sitting is associated with increased risks of obesity, unhealthy cholesterol levels, high blood pressure, heart disease, and type 2 diabetes. Additionally, sedentary behavior is known to weaken muscles and bones, leading to decreased mobility and an increased risk of falls and fractures, especially in older adults. Moreover, excessive sitting also correlates with a higher likelihood of developing certain types of cancers, such as colon, lung, and endometrial cancer. Therefore, the cumulative effect of these detrimental health outcomes can contribute to a shorter lifespan.