Replacing one hour of sitting each day with walking can decrease the chance of early death among seniors by 12-14%. Researchers also note that swapping one hour of sitting each day with standing results in a 5% decrease in the risk of premature death. On average, people over the age of 70 spend around 65-80% of their waking time performing sedentary activities, so substituting some of this time with standing or light physical activity could have a positive impact on their overall health.
International Journal of Behavioral Nutrition and Physical Activity, September 2015