There are many things that can affect a person's health but not all can be controlled. For example, genetics are what people are born with and cannot be changed. Additionally, global and environmental situations can change but it takes an entire community; so, one individual cannot change these factors. However, one person can change their own lifestyle, assuming they have the willpower.
Capillaries are one cell thick and so this makes them very thin. capillaries are also arranged in networks known as capillary beds, and thus multiple capillaries are spread over a large area.
