Answer :
Based on rate-of-living theories that focus on energy use, the single most important thing which people can do to increase their life span would be by increasing their physical activity and focusing more on physical fitness.
The rate-of-living theory which is of aging states that people and as well as the other living organisms have a finite number of heartbeats, breaths, or other measures, and that they will die once they have used those up.
However, the regular physical activity is one of the most important things which you can do for your health. As, being physically active can improve your brain health, reduce the risk of disease, help manage weight, also it strengthens your bones and muscles.
Hence, in short the single most important thing which people can do to increase their life span would be by increasing physical activity.
To learn more about physical activity here:
https://brainly.com/question/1506043
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